Multisite and WordPress

Hi all- I have a WordPress site with multisite installed. I, unfortunatly, have GoDaddy Hosting. As you may be aware, GoDaddy does not allow sub-domians with Multisite.

What I am wanting to do is create a network of multisite site’s. I want an end user to be able to create them (like wordpress.com does), but they will only be limited to sub directories, so their sites will be mysite.com/theirsite. Is it possible to map a domain name (theirsite.com) to mysite.com/theirsite? (My idea is simply a niche network, so users can create their own site, I am not mimicking what wordpress.com does)

Also, what is the best way to have end users be able to map their own domain? Is there a way to charge for, say, an ad free site, using Multisite? Would Woocommerce do the trick?

Thank you.