Price and cost are two different things! Price is what you pay when you purchase a product, but cost is what you end up paying for it over the course of its lifetime or for as long as you own it. So it’s usually smarter to pay a little more for something at the outset and get a better quality product rather than pay for poor quality over and over again for years afterward.
Certainly, my best piece of advice would be to look for a reputable window company, a company that will send a professional window consultant out to your home to understand your needs and the project, to give you design ideas and suggestions, and to leave you with an accurate quote and a timeline for completion.
Just one more note: You said this is a 40-year-old home. In that case, make sure that you test for lead before you begin any renovations. Homes built prior to 1978 have to be tested for lead. Safe work practices must be employed to that window installation. It’s not difficult and it’s not expensive, but there are some steps that have to be taken during the installation so that lead is not released into your home when the renovations begin.
So when making your decisions, make sure you are dealing with a lead-safe certified company and that your consultant can explain that to you. They will know what needs to be done and they are educated, equipped – and certified – to carry out the installation according to the new laws.