Recommendations for disco backing tracks

Hi there,
 
I have a disco band (classic EWAF, Kool & the Gang, KC etc.) and we have voice, drums, guitar and bass. We have struggled to find a keys player so we're looking into backing tracks since there is so much brass/strings.
 
1. I found one decent provider selling professionally mixed backing tracks, but they are a bit expensive ($15-$20 depending on volume). Benefit - I don't have to do anything, and they provide a solid intro/outro option (many of these songs fade out so it's good to have a defined ending). Down side - can't make them longer or shorter, add solos, edit instruments, do medleys, etc. Expensive.
 
2. The alternative would be to make my own using free MIDI files that I find online but...
- What's the quality of these MIDI files?
- Is it easy enough to use Sonar to edit these MIDI files and make them sound good enough? Then I can add a click track pan left, move all the other channels pan right, and should have a decent product?
- Should I also invest in BIAB to create some additional back tracks?
- I have an old Roland Sound Canvas SC-55mkII - will it sound better using the software synth or going out with MIDI to this sound module? (assuming I can control multi-channel MIDI with Sonar in a live performance?)
 
Thanks for your advice,
 
PL

2. The alternative would be to make my own using free MIDI files that I find online but... 
1 - What's the quality of these MIDI files? 
2 - Is it easy enough to use Sonar to edit these MIDI files and make them sound good enough? Then I can add a click track pan left, move all the other channels pan right, and should have a decent product? 
3 - Should I also invest in BIAB to create some additional back tracks?  
4 - I have an old Roland Sound Canvas SC-55mkII - will it sound better using the software synth or going out with MIDI to this sound module? (assuming I can control multi-channel MIDI with Sonar in a live performance?)  

1 - Some good, some mediocre, some suck. Its a mixed bag. You may have to search, download and audition many files to find good ones. I know there's a good one of "I Will Survive" and others if you look hard enough. 

2 - Depends on how good of a musician / arranger you are. Yes, you can pan any MIDI track in any direction you want to go. In a club that is not very important because if you pan too much, half the club won't hear half the instruments. 

3 - I've used Band-In-A-Box for ages. I don't know how good it would be for this application. Its really designed for Jazz covers. If you're playing disco music in a club, people want it to sound like the record. 

4 - The Sound Canvas will work fine. Most of the MIDI files you download will be General MIDI files. The Sound Canvas is a General MIDI synth so its a match made in heaven. If you don't want to lug the SoundCanvas around, use the TTS-1 softsynth in Sonar. 

 Eblue was the late Mike Petery that plays drums on many of the
 big disco songs we all know so well, hand full know this .. Jon