I use Paypal dozens of times a week for my design business.
I really wish I didn't have to (but why I do is another story)
I'd be very careful If I were you. The process is very much swayed in the purchasers benefit and they can cancel a payment at anytime they like- they money is paid back into their account and there is very little you can do about it.
If you cannot prove (with a Post Office recorded delivery receipt for example) that you have literally posted a product to the purchaser then there is absolutely nothing you can do about someone who instigates a charge-back. I used to sell remi hair online- and was naive enough in the early days to send it recorded and then chuck away the chitty when It'd been delivered. Little did I know that people would purchase the hair (which wasn't cheap!) and then cancel the payment via Paypal, get their money back AND keep the hair.
A client of mines credit-card company recently "clawed back" a payment from my Paypal account for absolutely no reason, and because I offer an "intangible" service (like yourself) - then there was nothing I could do about it.
AND I was then charged a fee (of twelve quid!) by Paypal for the "investigation".
So I lost the fee of the work and was charged for it as well. Mental.
Frankly, it's a disgrace- but then idiots like me keep using them!
For every £10 I make- they take 54p....so, it's really not that cheap either.
** I must add that the client was good enough to resend the payment to me! But that doesn't always happen.