Hi,
I have know idea of the print run of Japanese cards, but I am sure there are less of them compared to English. Pro Shop owners in Japan  that I have talked to say that they sell about 70% more English boosters than Japanese.
The main reason is the price, English are about 20% cheaper than Japanese.
Pre Releases and PTQ (sealed events) are usually with Japanese packs, but most other shop sealed tournaments, English packs are used.
I started Magic when Saga came out, so I don't know too much about Japanese Mirage.
I do know that the average player here plays magic for only 2 years than quits. So, most of the cards that people have in their trade binders are from the last 2 big expansions. I am seeing less and less of Saga and older.
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I wanted to post a reply to this, but couldn't:
http://www.themanadrain.com/forums/viewtopic.php?t=16151Someone wrote about me:
Micheal French. He's on Motl (if you need a link to his e-mail is in my references [sig] ) I've dealt with him numerous times (and he gets an A++++). He lives in Japan and has quite the impressive collection. Drop him an e-mail and see if he can pull some strings, but keep in mind he charges top dollar for his stuff, he'll charge a bit extra (cash wise or throw-ins) if you ask him to get a specific card not on his list and depending on how hard it was to get that card he might tack on a bit more.
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I price my good Asian stuff @ the same price as English ebay high. I price my timmy cards lower, and my casual stuff that if I can get cheap I try to sell at a cheap price. Some very playable type one cards, I let demand figure out the value. I know my prices are cheaper than shops sell cards in the states and what dealers charge at events. I have been charging $5 for the Japanese Mirage Tutors, I sold at least 15 of them in the last two months, I just started charging $6, but after reading these post I will have to bump up the price a bit.
---Michael