Hey dude. I'm a fifteen yer old doing pretty much what your doing (exept I'm doing it as part of a rap band). When i was first looking into samplers I found quite a few in the same sort of price range. Although some seemed to have more features than others, I ended up choosing the Yamaha SU10. It does the job nicly. Unfortunatly they dont make them anymore, but you can still pick one up from http://www.normans.co.uk for around £180.
If ya wanna talk bout it more, mail me on "fatspliff@ganja.com"