You know, it shouldn't be too hard for somebody to wedge cordless phone guts into a traditionally shaped business phone handset. You'd have to use a more expensive lithium-ion battery to get long talk times without a bulky battery pack, though.
Incidentally, when Googling for cordless phones, I found what looks to be a semi-decent vendor:
Cordless Phones America carries phones from all the usual suspects in all three major frequency bands. Probably one of the more unusual phones I've seen there is this $70 Uniden "submersible" cordless phone.