Re: Help, should i buy
Just because you ask a friend or coworker for a lead, does not mean that you are absolved of your due diligence. You must check into everyone you hire, unfortunately. Most states have some wort of governing board for contractors, you can check with them for complaints and problems regarding the contractor.
It would also seem you need to find better friends and coworkers if this is the quality of tradesman they are offering. It really isn't that difficult to find good tradesmen, but you DO have to stop looking under rocks and bridges in your search for them.
Specifically on your window question, as Jack points out, if the windows are the correct size, then it's a great investment, if not, then you're merely throwing away another $300. Secondly, why were the windows being replaced? It is quite likely that they needed to be, so again, a waste of money for you to buy and try to install in your house.
If I were you, I'd look around the city for a local window builder who makes the original windows. If you've got a decent sized or multiple "historic" areas, then you've likely got some local suppliers who cater to the needs of these homes. I have such a manufacturer in my city and the last full sash and casement I bought from him was in the $400 range, granted, this was about 12 years ago.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!