Like Alan said, I too have a limited budget but I've managed to build a small collection of games so far. And if you're lucky, you can find good deals at the sites he mentioned. I got Super Mario 3D Land, which is old but STILL goes for $40 used, for $30 on Amazon, new. Street Fighter IV, $10, like new. And if you register your games on Club Nintendo, usually earning 40+ coins a pop, you can exchange the coins you get for 3DS downloads, most are around 150 coins. So far I've gotten 3D Classics Kid Icarus and VC Metroid II: Return of Samus, just for registering games I'd bought.
If you shop specialty stores or retailers, ask about their membership or rewards programs. I joined GameStop's Power Rewards when I got my 3DS, and I get points for every purchase. Granted, it's a paid membership (and you do need a LOT to exchange points for anything), but they email me promos and coupons all the time. I got two used 3DS games with a third one free. And those used games? They had the Club Nintendo inserts still, unused.
Damn you and your awesome club nintendooooo.
Europes is utterly filled with suck. No monthly download for coins (we have "stars" here. wish they just did do the coins thing) and literally every item you can buy is a useless piece of crap for wii or ds. Merch nobody in their right minds would want
