If you can, make sure you plug it in and fire it up when you go look at one. If it starts off a little slow, and you'll be able to tell, "this doesn't sound right", tell em thanks and keep looking. I bought what I thought was a nice craftsman but I found out the motors tend to go pretty easily on those.
Just try to get something with at least 1/2 HP, preferably more. I know it's hard sometimes to get what you need without spending some $, but you'd hate to spend $100 now, only to realize you just blew your $100.
Good luck tho. When you get it, you'll see it's the most versatile tool in your army.