Hey, I was just asking for this also, I play a lot of jazz piano, so I'm always using an accompaniment, whether it's a metronome or, like you, preferably a drum machine. Steinberg has a program out called
Groove Agent that lets you easily pick a style you want and it will just play along. i've used it and it's pretty good, but it might be more expensive than you want. What I settled with after a LOT of searching for this exact sort of thing is that I got a looped sample CD that plays jazz brush drumming (which is what I wanted) and I just loop those wav files in my sequencer program. It works really well. A good program to play loops with is
Ableton Live, which might also be too expensive for you. You can also load it in the popular freeware sequencer (I forgot the name), but you won't have Ableton's nice looping features.
Yeah, I've looked for this a lot and sadly it's not really out there. Actually, for me it's difficult because I'm looking for light jazz brush drumming, which is very difficult to find. For most other popular styles, it shouldn't be too hard. Groove Agent would be the easiest to use if you can afford it. There's also a program called Band-in-a-Box that can be used for just drums, but that's also a little expensive. Good luck!