b18b or LS is the cheapest way to go, only about 1500 if you look around. No Vtec but nice and tourquey
b16asirII, has vtec, tad more than the LS, less trq, more HP, higher reving
b18c or GSR, has best of both worlds, ls's trq and the b16's hp and revs (has vtec)
B18c5 (specR, typeR, ITR ect.) A higher reving version of the GSR, better tranny, LSD, basicly the Holy Grail of the B series engines, will be most expenisive
Or there is the H22, if you have autoX in mind, this is NOT the swap for you. It is a very torquey engine and high hp but because of its size, new mounts are needed and also some modifaction to radiator (many just buy new ones.)