How expensive is too expensive for replacement windows?

[Nicholas Standford]

I have a townhouse built in 1968 with all original windows and im looking to upgrade. Im currently taking bids for th job which comes out to be 26 windows in total and im finding there to be a large swing in the quotes im getting. So far my lowest is $12,500 and my highest is $26. Ive done my reasearch so I know a ****** window when I see it but my question is, is there enough of a return on windows if I go with the higher wnd options?