About $1450, installed at a Ford dealer, with a 1 year warranty. That is
cheap for a dealer installed reman transmission.
For used, check out
Car-Part.com--Used Auto Parts Market, and locate a used box near you.
I've done a transaxle replacement in a late model Escort before, and it's very simple (for a trans replacement) and straightforward to do. If I remember correctly, the only special tools needed is a set of triple square bits (from Sears... $20ish) for the bolts that hold the axles to the differential. Aside for the axles, you have to remove the subframe, a trans mount, bellhousing bolts, and a TCM connector, and the tranny will drop out the bottom with a floor jack.
If your buddy has some mechanical knowledge and a place to do the job, he could probably be out less than $200 total.