There are several types of windows as far as construction goes and vinyl is only one of them. There are also several types of vinyl windows. Generally, the stronger the construction of the window, the more it will cost. There are exceptions though because some name brands command a premium price when their construction is not better or not enough better than the other brands to be worth the difference.
I would not recommend that you buy vinyl windows from some sales person or company that is soliciting you. Do your homework. Ask around. Check prices at do it yourself stores (who almost always have a list of contractors that they recommend). Check with the better business bureau.
A reputable contractor will do a thermal survey of your existing windows and again one after the new ones are installed to prove the energy savings.
Prices can vary immensely. When we replaced 12 double hung windows on our very old house, I ended up doing the installation myself (it's really not that hard) and paid the same for 12 windows as the salesman who came to our house wanted for one!
Basically, buyer beware!
Vinyl are longer lasting and cheaper than wood . The best would be like a wood core with aluminum, but you only need those if you plan to be in the house for ever, if you only plan to be there about 3 -6 years, the viynls are the way to go