my mate did it in his backyard, long as your a bit mechanically minded and good at logical thinking its def easily achievable.. y pay 4k if u can do it in ya backyard, and know where every bolt went and no how to fix most problems that might come up?? thats worth more than 4k IMO
my mate did it with motor box loom, pretty sure he paid about $2500 for it from an importer.. prices vary between them.. or u could look at a ca18det swap those motor box looms are pretty cheap sub $1500 if u hunt around..
s13 front struts and LCA's can be used, search on here for "s13" theres like a 15 page write up on it..
theres a guy on here who mounts sr20's or maybe it was ca18det's to ae86's but i think the crossmember are interchangable and u might be able to use the modded mounts then just make up a gearbox crossmember like my mate did, the only big problem that i know of is the clutch pedal setup is a pain in the ass, bit of grinding for the gearbox to fit in, might have to move the handbrake back abotu 20mm to clear the gearstick..
any questions hit here up i remember a bit from what he did