Midis are great Bill!

Many people scoff at the quality, but unfortunately (or maybe I mean fortunately) Midis are only as good as:

1. The quality of the file itself (realistic drum parts, lifelike horn arrangements etc)

and

2. The "Sounds" themselves (in other words, your Midi player).

As for places to purchase, I'm in Australia and thus purchase from a local site (Gold Coast, Queensland) but I've found the quality DOES vary, and not every midi has wowed me, but it's safe to say, generally, the best quality files are to be found for purchase. I have many sequences that ARE free (found on the net) but I've had to do extensive searching for good ones, and even THEN I end up either re-sequencing certain parts, adding in parts from scratch or at least tweaking and re voicing the parts extensively to suit my keyboard.

If you do go the Midi route, you really must end up doing the latter - if you don't, well, you'll get what you deserve if you know what I mean....

Good luck!