When I picked up my 360, I traded in my PS2, my Xbox and all the games I had for both (about 20 of the "must-haves"). I got about $60 for all of it. This was over a year ago. You're not going to get anywhere near $200. Sorry, trading is a great way to save money from game to game, but when you're looking at bigger purchases you have to weigh your options.
Are you EVER going to play any of those PS2 games ever again? If you're not, then just trade them regardless of what you get. It'll be better then them sitting around doing nothing. As far as I know the PS3s are no longer backwards compatible, so you'll need to keep your PS2 to play them. Just some things to keep in mind.
All I have to say is the PS3 is definitely worth the $299 (in Canada) now. Great exclusives like Uncharted 2, Demon Souls, Infamous and Ratchet & Clank definitely make this system worth it. Used to be a 360 guy, but I'm slowly favouring the PS3.
Good luck!