Yesterday I was at a convention in Sweden and had some success with (second place at the main event and second also at a side event) the following build:
Lock
4 Tangle Wire
4 Smokestack
4 Sphere of Resistance
2 Thorn of Amethyst
3 Crucible of Worlds
1 Trinisphere
Creatures
4 Goblin Welder
3 Gorilla Shaman
2 Solemn Simulacrum
Utility
4 Serum Powder
4 Bazaar of Baghdad
Mana
5 Mox
1 Black Lotus
1 Sol Ring
1 Mana Vault
1 Mana Crypt
1 Tolarian Academy
1 Strip Mine
4 Mishra's Workshop
3 Wasteland
4 Mountain
3 Barbarian Ring
Sideboard
4 Leyline of the Void
3 Jeser's Cap
2 Powder Keg
4 Granite Shard
2 Duplicant
Meta: A lot of GAT/Flash and some combo, no other workshop-decks (I suspected few WS-decks which explains the lack of artifact-hate in the board).
Comments on the performance of the deck and card choices:
Serum Powder: I tested this for the first time this weekend and found it to be very solid. It almost guarantees you to find an aggressive start with a lot of options. You will almost certainly draw a FoW turn 1 and if you have any more gas on turn 2 (which is rather likely) the game will look very favourable. It also enables running Leyline in the board which I have not been so impressed with in the more classic UbaStax-builds and it helps finding Jester's Cap in important matches.
Gorilla Shaman+spheres vs. Chalice: The focus of the deck is all about getting a hard lock and to eliminate enemy permanents. I wanted to try Gorilla Shaman and extra spheres and how it works with smokestack. The advantage with Shamans is obviously greatest when you are on the draw, since you can act after the opponent has played his moxes. Beside this he is also a blocker which is important in the Ichorid/Flash machup. The backside with Shaman/spheres is the disability to include Chalice for a decisive Chalice@1 which is imo just getting better and better and is also very solid on the draw.
Solemn Simulacrum: Solid blocker and enables red mana for the other seven creatures in the deck. He is very good with Smokestack+Welder since you can run Smokestack@2 for a long period of time. Solemn is very good vs GAT/Fish/Flash/Stax/Workshop/ and very poor vs. combo. The biggest drawback with the build was the manabase which relied somewhat too much on Solemn. This lead to a weak position when boarding against combo since I wanted to keep my Shamans and take out the Solemns. The result was that I was forced to take out also some Shamans which might have cost me at least one game but that is of course difficult to tell.
Tangle Wire: Always better than I usually think before a tournament. The weak matches are Flash and Ichorid but in all other matchups it is very good. Will create welder targets which is easy to forget but a very nice feature indeed.
Crucible of Worlds: Were terrible all day, always boarded them out. I knew there was going to be very few WS-decks in the meta but chose to include three in the main deck just in case and not focus too much on Stax in the board.
3 Wasteland: I think 4 is better but it is not so important as to motivate the inclusion of Crucible. One Wasteland/match is usually good enough since basics are so frequent. With the heavy amount of red in the MD I felt forced to include more red mana so one Wasteland had to go. Serum Powder helps here though since it lets you find a Wasteland in matches where it actually matters.
Barbarian Ring: I am not so impressed with this since the damage might help the opponent to finish the game. In this weekend (with Solemn) it would have been better to run more Mountains instead.
Leyline: Very good with Serum Powder. Won me several games where it delayed the opponent enough to build up a hard lock.
Jester’s Cap: Only got to use it once but it is very solid right now (combo, Flash and the growth of Tyrant decks).
Powder Keg: The idea was to use it vs. Zombies (Ichorid) and Empty the Warrens. Never faced either of them.
Granite Shard: Good vs. Oath, Fish, Ichorid, Flash and Welders. I used it against Fish and Flash and it was great.
Duplicant: Good vs. most of the decks right now. I even board them in against combo sometimes if I suspect they might have Tinker/Colossus in the board. I used it in several games and even though it is not too easy to get out it is still a game breaker when it does hit the board.
Uba Mask: During my testing I found Uba expensive and not the bomb it used to be. I replaced them with Tangle Wires which is cheaper and supports the general game plan of this build. Uba Mask feels more like a luxury card than a good-enough bomb right now.
Bazaar: Without any doubt one of the best cards in Stax even without Uba Mask. It filters dead cards and thereby keeps up the tempo of the game plan (which is the most important function) and it sets up Welder-brokenness and an occasional Crucible-Waste/Strip.
General thoughts/feelings: The serum powder almost guarantees a first turn Sphere or Smokestack with an additional turn 2 bomb. This will in most cases draw a enemy FoW on Turn 1 and if not, the opponent will face a difficult game state on turn 2/3. The deck was very consistent during the days of the convention and I like Leylines as they buys valuable time in, otherwise, very difficult matchups. I lost the final (2-1) in the tournament to a good combo-player but I am not too disappointed since he drew the nuts combined with good artifact hate in the two games he won and my mediocre draws were just insufficient to prevent his development. This will happen some times but it was just a shame that it happened in the final.
I am not completely satisfied with the build and will work on improvements. My ideas so far are these changes in the MD:
-3 Gorilla Shaman
-1 Solemn Simulacrum
-1 Crucible of Worlds
+4 Chalice of the Void
+1 Karn Silver Golem
This will somewhat weaken the Ichorid-matchup pre-board and also the Stax-matchup to some extent, but will strengthen the deck against everything else imo.
I am very thankful for any suggestions/thoughts on Bazaar Stax/Uba Stax and would very much like to start some discussion on what strategy to use against different kinds of meta. Has anyone tested it against MUD/Mono

-Shop (which seems to be on the rise, especially in the States)? What is the situation for Stax against different Tyrant decks?
Are there any benefits of running locks instead of creatures right now? I am not an aggro-player and would rather play combo than adding creatures in my WS-deck.
EDIT: Corrected some spelling errors. I apologize for my poor English.