You're not competing with Amazon, you're just buying from Amazon.

You should be selling your expertise and installation, plus can make a few bucks on the products and maintenance (if needed).

I'd rather make less money off the solid product (with zero return trips) versus make more money off product that can and will become a service problem that eats into any of the profit that was made.

I mean, the difference in pricing is what, a couple hundred bucks?? You'll make more with the abundance of referrals from your customers.