The costs are for general fabricated beam members such as W, WWF, S, C, and L sections(c/w copes and holes for end clip bolts). HSS and other tubing may cost more therefore try to avoid HSS when possible. For plates, remember most steel sheets are supplier in a 4 x 8 or a 3 x 6 sheet size and this will dictate the fabrication cost. Smaller more complex fabrications will drive prices up as well if you are supplying steel for a highrise, the costs will decrease. Remember buy bulk. Most suppliers have a beam say W8 x 18 that is mass produced and an engineer trying to reduce the steel will only end up paying premiums for a non-stock section rather than using the industry norm!!
As for supply, fabrication and installation costs, some where around $5/lb - $6/lb. USD (Again depending on location!!)