$1800 for just the basic tranny refurb, then you've got the torque converter $$, and any upgrades like 5 disc clutch packs and upgraded forward planetary gear, porting for better flow to the torque converter (a must do for longevity),
shift kit.... $3100 isn't a bad price if its done right. The E4od is one of the most complicated trannys on the market and isn't cheap to build right.