Word to the wise: You get what you pay for. If you buy this thing please don't judge pellet cooking by the results. There are some incredible, fantastically capable pellet cookers available but the technology is still expensive because the pellet share of the outdoor cooking market is still tiny compared to charcoal and gas.
If you have not cooked with pellets before, see if you can get some experience from a nearby pellet user or do some reading up. Fact: you can get great flavor and control on a pellet cooker but your approach and recipes will need to be adapted. This is a process, not an event. Also, if you like smoke as the only or dominant flavor in your cooking you might be disappointed. You have to learn how to instill smokiness with a pellet cooker and over-smoking is very hard to do.
If you were looking for a new gasser, $500 would get you a pretty good one. In pellet cookers $500 is extremely bottom of the line and even a quality used one in good shape will go for a lot more.
Hub