Well, first off, it seems like you need to make up your mind on which cases you are going to use before you commission anybody to do cover printing/cutting work. If you're willing to settle for the DS case route, so that you can use the bounty of GB covers available on the site, then I would be glad to help you with the printing/cutting process, plus a small nominal fee for the labor, of course. (Cutting things out is a tedious process, remember that.

) I use, as Arseen suggested, an Exacto knife with a metal ruler. The edges are almost always perfect.
But, if you want to use EU cases or 3DS cases, that will be a different story. Theoretically, you could simply stretch/skew the DS covers to fit the dimensions of EU/3DS cases, but if you want them to LOOK decent, you would probably want to edit each cover individually and change only the spine to be the proper sizes, because (if I'm not ill-informed) the spine is the only thing that changes size from US to EU cases. In other words, that would be an EXTRAORDINARILY tedious process that you would likely have to undergo yourself. But, like I said, if you want someone to do the cutting for you, I can.
Also, about "mangling" the boxes to get the games to fit, it's really not that bad. Especially once you put the games inside the cases, they cover up the places where you cut. That's the idea, for the game to hide the scars of the case itself.
As for printing covers, I've been to several Staples, Kinko's, and other various print stores in my area and they all turned me away because they noticed all of the copyright logos on the covers, and they just didn't want to deal with it. Luckily, I go to a University with an on-campus print shop run by students who couldn't give a damn about what I'm printing, so that's where I've been going to do my printing.
As for Virtual Boy games, I have my entire collection cased in "mangled" DS cases that work just fine.
So, if you want to commission my print/cut service, I'd be more than happy to oblige you on your casing quest. But, Photoshop work goes too slow for me, unless you want to pay BIG BUCKS for commissioned editing work for cover case conversions. That's really not something I want to do. Unless the price is right, I guess.
Send me a PM if any of this interests you, or you have any questions for me.