I paid about $400 to get my main leafs replaced and the rest rearched- The replacement springs are about $400.
If you've got to replace them anyhow... think about going with wider springs. I think Carter's has a kit for the conversion. The wider spring kits cost about the same and include the shackels, bushings, bolts and frame mount points. That is what I'll do next time around if I don't go to coil springs and a 4-link set up, which I guess would cost about $500 to buy and put in myself.
Wider springs stand up better to more torque and heavy loads- Here's an article on it:
http://www.oldchevytrucks.com/cgi/htmlos.exe/002026.4.2678320566400011432 Someone might chime in with what factory wider springs you could get locally and bolt in with the new mount points. I'm guessing Blazer maybe? There might even be a thread on it here somewhere.
Your local spring and suspension shop can definately make you springs that'll do what you want in terms of lowering and handle what your truck's got to dish out, and maybe at the same cost as ordering springs from Patrick's or No Limit.
