I bought a Weber Q 320 Propane BBQ last April/May at Home Depot for around $330.00 bucks or so:
http://www.homedepot.ca/product/webe...s-grill/918130
I just looked and it's $439 now though! But it's worked out great and as I was getting the last one in stock I also had a random employee and 2 random customers in the store tell me how great it was. So I'm not too surprised it went up a bit in cost but it's still under your max. The sides fold down as well so it doesn't take up too much space.
Only thing it lacks is a top grill but I find that's not a big deal, just turn the heat down lower. Also has 2 seperate burners - a ring that goes around the outer part of the grill, then a single one that goes down the middle. So you can adjust the temperatures that way too.
Hope that helps. There's also a smaller/cheaper one that you can actually easily dismount from the actual stand and easily take with you in a car or on a quad if you go camping a lot as well.