We didn't discuss price in advance. I trust that these guys charge what is fair. I just discussed the fact that we wanted to do it as some bike shops have very negative feelings about people who buy bikes on-line. And that may vary depending on the bike - we were buying on-line because that was the only available option. If you're buying on-line to save a couple bucks over the bike shop price, the reaction may be different. But it's good to talk to them in advance in any case as they become involved in the process and may have alternative ideas you would want to consider.
Most of the on-line bikes are substantially assembled anyway, so $100 should be in the ballpark in most areas I would think. People wanting to charge a good deal more might be telling you they really don't want to do it. (And some shops don't because they don't want to be blamed if there are issues with the bike. But that's where starting to build a relationship in advance comes into play. They can get a sense as to whether or not you are the sort of person who may be trouble down the road if there are any problems with the bike.)