Grass roots? I’m selling sample packs, not homemade jam 
Gumroad is a tool/service. I pay for it because it provides hosting, payment processing, and customer support, as well as analytics and basic CRM tools.
Paypal takes a cut. Private web hosting will cost you money too. Replying personally to every request for a sample pack, even if someone doesn’t want to pay for it, takes time.
I’m running a business (while studying full time at that), there are some things I just don’t have time for. If my business grows and I need to hire an accountant, would that be wasting my money?