How are the tires you're running right now? Are they good enough still to stick with them until you can save more money to increase your budget? Unless you spend a lot of time ripping 'em to shreds a set of tires will last a long time; you ought to make sure you get the best ones you possibly can.

Otherwise, there's the classic Radial T/As to go with, I believe they're about $80/tire. They're nothing too special, and I can't give you a valid opinion as the ones I used to have were nearly worn out when I got 'em, but they did their job.