After my 4th window regulator failed, I decided to try something new and buy a rebuilt unit from the guy on ebay. He also has a web site www.regulatorusa.com
The GM price for a new regulator is about $337. GM Parts Direct charges $212. I paid Alexander at Regulator USA a total of $173 with shipping, and he promises a $40 refund when my broken unit is returned to him. So the net cost is $133 with a six-month warranty.
I got the regulator two days after I ordered it via UPS. It looks brand new, and after I installed it...everything seems to work just fine.
Assuming that I get the $40 core charge refundeed, and that the part doesn't fail in the near future...I give Alexander very high marks.