Hi Sean,
For that kind of money, you can probably get a Emu E-6400 (non-ultra) sampler and have money left to spare. It has many expansion capabilities so you can grow with it. You can put in as much as 128 MB of memory. That is a lot. This gives you about 12-13 minutes of stereo sampling if I'm calculating correctly. E-mu has some refurbished ones (that come with a 90-day warranty) for $700-800. Keep in mind that this is not an Ultra model although you can upgrade to an Ultra when you're ready. At that price, you may be able to afford a sample CD Rom as well.
If you are prepared to spend slightly more, you can get a brand new E-5000 Ultra for $1300-1400. The Ultra models give you this feature called Beat-Munging which allows you to manipulate your loops in many different ways. The Ultra models, because of their faster processor, have quicker screens and tighter MIDI timing. Check out E-mu's website for what is possible.
I think that these are the best deals in terms of price vs. performance. Aside from that, you'll be able to pick up something like a Akai S3000 or something similar for around $1000. With the S3000 though you're limited to a maximum of 32 MB of RAM.
Myself, I'd stick with either an E-mu or an Akai sampler. The Roland S-760 is nice too (I used to own one) but it is limited in features compared to today's samplers. Too bad that Roland has not come up with a new sampler offering since the S-760. I would have bought that instead of selling my S-760 and buying an E-5000 Ultra.
HTH, and good luck
Fernando