Is there anywhere I can build a very simple payment page to charge a one-time fee from my customer? I can't do programming, so I need something extremely easy and all I need is just a SINGLE payment page.
For really simple you could just use something like PayPal. Another option would be to use Stripe Checkout. Either don't require a whole lot of programming skill, although PayPal is probably a little easier as you can just direct them to the PayPal site to pay you.
Coinpayments is a simple drop in clump of code if you want to get paid in crypto: