If you don't want to go back OEM...There is a vendor on Ebay that sells a complete set of HD bilstiens front and rear for $280,free shipping!
http://stores.ebay.com/Thepartsladi
search for bilstein 4runner
...Or this place $170 for front or rear set(if you just want to do the fronts or the rears)
http://www.autocarparts.com/part/819/34/