I have been thinking about selling (or trading) some games with other people online, but I'm not sure how much it would cost to ship them (about 2 or 3 PS2 or Wii games)

I've been thinking about using these:
http://www.usps.com/shipping/prioritymail.htm

Has anyone used these before?

I believe the flat rate boxes run about $9 or $10 to ship with (t's been awhile since I've used one), and you'd have more than enough room. The flat rate envelopes are cheaper, but offer no protection to what you're shipping at all. If you're only going to ship 2 games, a plain padded envelope might be a better deal. Shipping two games first class wouldn't run you much more than $5, I would think.

the small flat-rate box looks like it'd be plenty big to ship a couple of Wii or PS2 games, and it's only like $5. I'd say go for it, but make sure you have insurance or delivery confirmation put on it (so whomever's receiving your games can't be all 'oh, they never arrived, plz to refund nao', y'know). a plain padded envelope isn't going to protect much either. D:

lol true, and thnx 4 the suggestions everyone!

Bubblewrap, mmmm.

o.O