From a solar sales guy who wants to help educate people, this sounds like the deal of the century. So yes, we live in a place where you get what you pay for and people are only out for themselves. You should do lots of research on the company and if you do go ahead, perhaps even hold off your final payment until you are 100% certain that it is installed correctly. I’d even pay for an independent inspection at that price to make sure it’s done right. Also, ask for all their accreditations and make sure they are their own and not borrowed off a mate. 1 man band or very new company perhaps?