I expect the bike dealer quoted you that high price because you didn't buy the bike from them. Some dealers are very resentful of bikes bought elsewhere and brought to them for service, particularly if the new bike owner expects fast or even free service, which sometimes happens.

Their attitude is shortsighted but probably what happened to you.

As a general rule if you buy bikes or components by mail order, either know how to install/service them yourself or plan on paying a significant premium to an LBS to do it for you.