@Vegeta.
The scenario you proposed now is far more troubling for the Gifts' player.
Both Tormod's Crypt and Echoing Truth can be considered good answers to Bazaars and Welders but you cannot simply put them into a Gifts as Needle or Darkblast and hope to be able to play them in the same turn, especially with the mana development at our disposal.
I try to elaborate a bit more on this issue.
In my experience, you have to fear the Bazaar-Welders recursion as a plague, so you have to do as much as you can in this turn.
If you pass without having done something crucial, you be completely smashed by his possible nasty artifacts' interactions.
You have to capitalize your cards trying to take care of the Welder, the worst things in his board.
Bazaar would remain active during all the match barring the presence of a single Stripmine in the Gifts' maindeck.
Having no data for this precise card's choice, I can assume that I haven't this card at all

My plans are two, really different and unluckily for me, not game ending.
They bring you in a good position but they didn't assure the victory.
(A)You can simply try to draw 6 cards thanks to TFK & Brainstorm, hoping to Walk once or to find one of the two maindeck answers or to be able to Tutor for them.
IMHO, this is a good plan, but the risk is high, because you have a lot of cards left in the deck and you cannot maximize the draws at all with this process.
(B)After a bit of thinking, I realized that you can Gifts twice, add more permanents on board and play a Walk, still holding that Brainstorm and that TFK in your hand.
( During this process I ended not being able to play Recoup+Y.Will because of a single mana missing

).
The process is really resources intensive, but you would end the turn with a better mana development, a thinner deck and a grave ready to be loaded into opponent's face.
1) You can play Mana Crypt and you have 5 mana on table.
1.1) You can play land and rise that count up to 6 but it would not be the right choice.
2) You can play Gifts for Tormod's Crypt, Echoing Truth, Academy and Lotus, using 4 mana but probably gaining additional 6 mana from the pair Academy+Lotus
3) You have now Academy+Lotus+1 mana floating for a total of 7 colured mana floating (UUURRRB).
4) You can Gifts again Petal, Mana Vault, Walk, Recoup with 3 coloured mana floating (UBR). Your grave grew a lot into this process and Y. Will would be game ending soon. You would probably gain Mana Vault and Petal. The total mana at you disposal would be UBR3. With a single additional mana on table you could have played Petal, Vault, Y. Will, Recoup for the win, but with this configuration you can only untap thanks to the Recoupped Time Walk.
It isn't the best play available.
But it is the one that help you much more than you can think.
You have all the Tutors ( except Mystical ) and Y.Will into the deck. You have other artifact mana fonts and your winners in it, too.
You board would be:
Island
Undeground Sea
Mana Crypt
Mox Ruby
Mana Vault ( tapped )
Academy
Your deck is 8 cards thinner than before and you have Brainstorm and TFK ready to use.
Calculating the cards that you used until now, you have played 12 cards before the two Gifts and you tutored 8 more cards after them for a total of 20 cards.
You have 40 cards left instead of 48 and there are better percentages of drawing one of the key cards for this situation.
You have 8 mana on board, all the needed colours and you can see 6 new cards thanks to TFK and Brainstorm yet.
There are a lot of cards combination that would put you in the position to win the game :
You can draw both Y.Will or F.F. or Mystical Tutor or Vampiric Tutor and kill the Welder and the game.
TFK+Brainstorm+F.F. would let you kill the Welder and gaining a lot of tempo.
TFK+Branstorm+Y.Will would win the game
Also, there are a lot of other combinations that can improve your board or give you additional tempo:
You can draw into FoF and other mana fonts
You can draw into F.F.-Vault combo
You can draw into Burning Wish and find solutions or Walk again
You would be able to add counter his artifacts with additional Drains-FoWs-Duresses for at least one turn, barring any grave recursion
I'm sure that this sequence of spells can "counter" by itself some of his possible way to lock you down.
One among Rod or Titan or CoW+Waste or Wire or Smokestack cannot be considered a real threat for the next turn.
Of course, coupling a lot of them would kill you.
On the other hand, while he can see 5 new cards ( bazaar, draw, bazaar ), he cannot active Welder during yur EoT and he have to resolve a single artifact to switch back something from the grave.
The small amount of cards into his hand can be considered crucial for us.
Eot he Bazaars once, draw 2, discard 3, hand size 2,
Draw phase, add a card, hand size 3,
He can Bazaar again, drawing 2, discarding 3 and remaining with 2 cards left in your hand.
In the process he would have probably discarded the overcosted artifacts, leaving the low cost ones into his hand.
If they are 2 Moxen, we are fucked up, excluding double counters' backup.
If they are a Wasteland and a Mox, he cannot prevent you from Draining/FoWilling it because of your good mana development
If they discarded shit, you can weight the need of a counterspell on that mox, comparing your board situation with his board situation.
He can even not use the Bazaar the second time if the cards drawn would have been really good, but there are really not so many highly probable cards' configurations that would help him so much.
The best play that he can stack could be this one:
- Discard Titan and other two other good/bad cards.
- Hold 2 Mox into his hand
- Draw a Wasteland, kill your Academy with it
- Resolve one of the two moxen
- Switch back the Titan killing both Island and U.Sea.
If you had not drawn another land during the previous turn, you would remain with useless Ruby, Crypt and a Tapped Mana Vault on board.
Game Over for us

MaxxMatt