Installing tall upper ball joints will accomplish the same as a gullstrand mod, which is to increase the camber gain, the difference betwen the two is the time and effort required... the Street-Comp Stage 2 Packages include both tall upper and lower balljoints, improving camber gain and roll center BEYOND the gullstarnd mod... (and it yields a .5-.3/4 inch drop...)
if it were me id stick to the tall upper/lower balljoint + adjustable upper arm in the SC&C street comp 2 package. aftermarket subframes are 4-10 times the money... the street comp 2 is 800 bucks.. markus us also a big ATS dealer so you might be able to inquire into the ATS spindles.... it is my understanding that tyler who owns ATS is continuing on a part time basis and only closed his vegas shop... so the spindles might still be available but they are 1300 for a pair... you do however save when that on the brakes....
(and heidts is a hot rod company, you get great bling, but crappy handling.... )
i saw Frank chimed in with the speedtech subframe.. i have dealt with both SC&C and Prodogy and can recomend both warmly... but since you are asking for handling on beer budget i strongly recomend that you call markus first: 610-346-8154
http://www.scandc.com/suspensions.htm