This whole Windshield thing strikes real close to home.
       I happen to manage a store for SAFELITE,Glass is really just glass
,but safelite will always try and sell their own product first,the biggest
problem is generally getting the part to the store without it getting
scratches or clammed on the edge .If you can get a piece that is in good
shape ,and are mainly concerned with price than use one of their manufactured
.but if you ask the order taker if you can get a (PPG,HBI,or sometimes even a
SIGLA or SEKURIT for the same price just for the asking.
       I do not recommend having your w/s replaced at your work or in your
driveway,most of the installers who are out in the field are overloaded with
jobs and their only concern is how quickly they can get on to there next job.
       If the w/s is cut out with a razor knife make sure that any and all
scratches are primed with a suitable "pinchweld primer" after the w/s is
installed make sure that it is sealed between the glass and rubber with a
URETHANE sealant,even when getting a NEW seal it still needs to be sealed.
       Before commiting to having this done purely by price and convienence
,think about the amount of grief that a bad job can give you ,every says that
they have a "warranty" the best warranty is one you never have to use.
       So in closing ask the questions listed here and have it done in a
store not on the road .
                                                            VWCREWMAN
                                                          20 plus years in
the glass biz
                                                                     my 2 c