I have an Ensoniq EPS sampler. It's fairly easy to use and you can play while
loading. They run for about $500-$600 used. You can also get an EPS-16
(upgraded version) for a bit more. their top of the line sampler is the
ASR-10, but that gets you in the $2000 range.
Roland recently came out with a sampler geared towards the DJ/Non-Musician
market (a more affordable one than their DJ-70 keyboard). I don't have the
model name off-hand, but it's in a drum machine-like casing. The quality
is quite good and the memory is expandable.
Elson