It depends what currency. Here in Canada, I got a powermac g4, dual 800mhz, 1.5GB ram, superdrive, iLife/iWork, CS3 and 10.4.11 installed for $250. This is an amazing deal (here in toronto), and I still cannot find another good deal like the one I got. I recommend that you continue to look for something cheaper.
For $400 I got a powermac g5, dual 1.8ghz, 1gb ram, so there are many good deals to be had.
I would not buy that for $500. The most I would pay, is $270-300 CAD depending on condition and software included. Btw, the g4 listed above was mint condition and also included an apple pro keyboard/mouse.