BMW X5 WINDOW REGULATOR REPAIR KIT REAR LEFT:eBay Motors (item 170398890180 end time Nov-24-09 05:22:26 PST)

What do you guys think?
I am going to replace my window regulator for the first time.
Should I purchase this cheap kit or get a new regulator for $60-80 off ebay?

Doesn't look like the kit comes with any instructions and this is my first time doing this myself