If you really like this guy (err should i say dont like Home Chepo), then why not just tell him your situation? That you want to have him do the work but his price is higher than other bids you've gotten, and can he do any better. I'm not very familiar with either brand so i cant say weather he's over charging or not, but $2800 sounds very fair for any bay window considering they are usually a 5-7 hour project when done start to finish (building and shingling a roof over it, triming the interior and exterior, putting shutters back up ect.) Most contractors are willing to negotiate if it means possibly losing a job all together, it never hurts to ask and this guy will probably appriciate the fact that you took the time to try to work somthing out with him.

I don't know if it's too late to help, but I did have another thought for you. Since both are offering you Simonton windows, the quality of the windows will be similar. You may want to base your evaluation on the quality of the installation and warranties. I good window poorly installed may not show problems for years. Who will more likely be still around years from now, the independent guy or Home Depot? Who will more likely come out and fix it for free, the independent guy or Home Depot? - Hope this helps!

A little more information would be helpful. Does the price include building a roof over the window? If so, is it to be a shed roof or a hip roof? Will it be shingled or metal? Does the price include grids? Is the quote with Low E H.C. or S.C. and does it include argon gas? Will the sidelites be fixed, double-hung or casements? Does the price include a "cut-out" or will it be installed into an existing opening? If a cut-out is required is the wall brick or a frame up wall?