I honestly don't understand why anyone bothers buying repro carts when you can get a single flash cart for $50 and play any translated ROM on it.
Either way, it's still "technically" "piracy", so why take up space for bootleg carts?
I would refer to my earlier "people are crazy and have too much money" rationalization of it... but...
I guess I just did. But people don't like it.
Edit: just so this message doesn't sound like i'm a complete asshole, I do get wanting to have the game for display on your collection, I really do. Nowadays, I rarely play the games I buy. The ones I do is mostly because I like them and I want to have them and keep them on my possession as a collection. Hell, I bought Ocarina of Time 3DS on launch because I really love the Original Game and I don't even have a 3DS yet!
It's just that a reprogrammed cart is not the real deal. It's something somebody made in their garage. It has no actual history other than "this is a piece of software that some fans had to work a couple months of their life so somebody could get ahold of it and then resell it for profit". If you don't have the original game, buying a repro is even worse: You're literally paying for two kinds of piracy: You're stealing the original code for the game plus you're paying a large amount of money to somebody that had nothing to do with the translation of that code. Technically, every pirate game is a repro. It's somebody elses code, acquired without any royalties or amount sold percentage being paid, copied and sold to you for profit.
For me, personally, a better scenario would be to buy the original, untranslated, imported Japanese game you so desire and keep that in your collection, proudly displayed (and maybe even sealed), and then use a FlashCart to play the translated version of it - whichever version you prefer.
That way you have a real cartridge made by Nintendo, something "exotic" from another region and was not released in the region you live, a real palpable object from the 90's that was in circulation, and you also get the experience the game through a device created for that reason alone. (well, and piracy). You would also be technically "in the clear" from a morally dubious point: You're just playing a "backup" copy of a real game you own. It just happens to be translated instead.
Not counting that having flashcarts is also a nice collection material - I have an original GBXchanger 64mbit cart for GBC that's quite rare nowadays.