used engines
if the person who lives nextdoor to you has an engine, and you see him break it in correctly, and you see it every time it runs, and he keeps track of how many gallons it has on it, yes this is way to much to do=don't buy used engines, more so on ebay.
To get started, there are many good motor's in and below your range on price, and the only one i strongly recommend is the NR n21BF or the limited edition N21, very good power, awesome on tune and will haul the mail, like $150 on a main right now, very good little engine. If your wanting more, the next step would be a NR P5xs, a little more $$$ but you are getting more for that amount.