not sure about your area, but here spring install is on average around 50 bucks per wheel. i'm sure if u are getting alot of stuff done, they would work with u on lower price. its really not that bad of a job to do yourself though.
4x4 here in glen burine maryland charged me 350 for install of my 4.10's and was going to charge me 250 for my eiback springs and tokico struts/shocks on all 4
but i have meet some cool people since i have left the import world friend of mine that races mustangs helped showed me how and i helped also hehe install my springs /struts and exuast for 160 hehe nice guy