The cheapest isn't always the cheapest (never is) and the most expensive isn't always the best. Check BBB for an accredited business which means it has no unresolved complaints.
Doesn't mean it hasn't had a complaint only that it has taken care of any and all problems once it was notified if it got one from the BBB. I only found this out myself recently after some A/C work was done and if they are not accredited I will not use them. You would be surprised how few there are in the A/C business. Windows now and found this thread via Google search.
Don't want Window World that's for sure. Later :-).
Product or Service Mentioned: Window World Window.
Monetary Loss: $4500.