We have one 5 min from our house. We have used them twice this year alone. We just do wash only and then take it home and buff and wax ourselves. We tell them to try to stay away from the window caulking (hadn't thought about slide seals). Haven't had a problem other than it can be a long wait depending on how many trucks are ahead of you. To me it saves my back and a lot if time if I time it right. I will be doing it that way from now on.
Here is a link to Pricing
. I think that like any other chain, it all depends on your location and who is working that day.