Hi! I live in a 1926 Tudor building that unfortunately had its original wood windows replaced in the 1980's. Now many of the white vinyl Nu-Sash windows need replacing themselves. The building has roughly 200 windows for about 15,000 square feet. It is not in a historic district. We are located in Michigan.
This building is a small housing co-operative and the 8 units are owner-occupied.

There is a lot of interest in replacing the double-hung windows. So far, four of the most dilapidated windows have been replaced by Sunrise windows using a local installer as a demonstration. They used the existing frames.

Our owners are most interested in reducing air leaks and also in noise reduction because of traffic.

Now we are starting the process of getting competitive bids. Are there economies of scale with vinyl windows? In other words, should we just contact companies and ask them to quote all the windows at once assuming that we would get the best deal that way?

We actually want to have the windows replaced in three stages - (1) the 65 windows over looking the parking lot, (2) the 8 sun porches and (3) all the rest except for the 10 original windows. The parking lot windows get a lot of sun so the vinyl is badly deteriorated but they do not require noise reduction. The sun porches each have 6-8 double hung windows. Is it better to get separate quotes for each of these stages?

We are interested in Sunrise (which is in Michigan) and in Okna. While we have contacted a couple of Sunrise dealers, we have not been able to identify any Okna dealers in southeast Michigan. Can anyone provide contact information for a dealer?

How much difference is there between Sunrise and Sunrise Restorations and Vanguard? Is it worth the effort to get the extra bids?

Any advice would be greatly appreciated.