3SGTE 4WD Corolla has been done before, especially in East Malaysia. Refer to this link from sifu 2o2r regarding a while AE111 4wd, I believe many more experienced forumers would have come across this before:
http://www.zerotohundred.com/newforums/toyota/262741-ae92-with-4wd-2.html#post3367306
Btw, 3SGE Beams isn't
that new either, the redtop that xMika is talking about comes from the ST202 Celica which was produced at the same time as the AE111 which carried the 20v BT engine.
I don't know about the price there in East Malaysia; 20v BT prices in Peninsular are rising but definitely not as high as the prices you quoted and definitely not much more expensive than 3SGE (if they are actually more expensive). Maybe it's just some lucky fellas who got good deals for their 3S.
Regarding your query, I'd say if you want a relatively headache free job, just go back to the tried and tested 20v BT; if you wanna be different and don't mind some extra hassle (and possibly extra cost) go for 3SGE Beams or 3SGTE. Mind you, 20v BT maybe over hyped but it is by no means a snail, I'm sure it would be a huge upgrade on your 4AFE and that you would be happy.