I know this has come up a few times, people asking how to do it... what parts to get... yatta yatta yatta.
Well, I figured since I am in the middle of swapping over to SPC upper A arms, Blazer spindles and brakes, and taller ball joints I could share a little info.
The cheapest way I found was buying the parts separately. I believe the price for the "set" for a g-body was about $60 US. Well I can say this cost a little less.
EAR-63010112ERL x2 (9.88 @ summit racing.com)
These are your actual brake lines, everything else listed will be fittings. I used 14 inch lines, but 12 will be good enough. 10 is too short, in case you are wondering. You can also go for the brake line that has a 90 degree bend in it, it will cost a little bit more, but make sure you plan before you buy and you should have significantly less problems.
next up is your banjo fitting. If you are using the stock calipers this part number 997631ERL is good enough.
7.39 x2 @ Summitracing.com
If you are using say, Blazer calipers you need more length or you cannot get a seal. I used part number 9978036ERL. 14.95 x2 @ Summitracing.com
Lastly you need the adapter to go from -3AN to the 3/8-24 brake fitting. Now anyone worth his weight in wrenches knows that -3AN and 3/8-24 is so close you don't need an adaptor... BUT this adaptor provides you with a way to fasten your new brake line to the frame using the brackets already there! Part number 989543ERL is what you need. 5.39 x2 at Summitracing.com
Total? 45.32 plus shipping, handling, and tax. Enjoy!