to answer ur question simply. it depends on wat type of metal is used, either it be mild steel or stainless steel, and if press bent bends are used or mandrel bends. if u just want a 'fix-it' type job, i say u shuld go with mild steel, press bent in factory diameter.
i dont think it is exactly worth paying extra for stainless steel as ur car is already old and may not be worth it. it depends tho, up to u.
if u shop around im sure u can find that u will pay, for a basic job in mild steel, press bent about $250-300 best price..
if its made in stainless with mandrel bends then u can be looking at paying between $350-400-450. depends on quality sizes and who u know heh
i recommed u get mild steel in a bigger than factory size (twin cam corolla--4age? no more than 2.5inch) with either ur press bends or mandrel bends. is the engine modded? or wil it be?
look around on these forums and im sure u will find wat pipe diameter will be ideal for ur application.