So there are really only 3 or 4 setups out there that would be a drop on and run type.
edelbrock which I think is closer to the 4k range
Mopar same deal
Fast as you saw,
and one place called budget efi or something like that that uses a chevy computer and sensors. Has a pre programmed eprom and they will flash it again for free based on what you actually run. About 500 less than fast but not as flexible.

Here is the thing. EFI is not necessarilly going to net you any better mileage. Just better drivablitly, cold starts and more consistant running in general.
So if you expect payback based on mileage, then I wouldn't do it.

I am currently trying to set one up based on the painless perfect managment system, and it will probably work out to be around 1200 when I am done, but it is no where near drivable yet.