Have they shopped prices? 4x T1 might be close to the next tier (T3) price. If you look at the advertised prices I doubt it, but, might be worth calling for some quotes to check.
I swear the wISP around here said they can get a T3 for $3K/mo (right now he's got 2x T1's). But it's been a while and I may have been out in the sun too long watching them do the install.