I had a paypal account before I started MSing. Originally, I only used it to pay for ebay purchases. The paypal account is linked to my personal checking account. When I used it in that manner, there were never any fees, but I only paid using paypal.
One time, I sold something on ebay. In order to be able to accept paypal and let the payer use a credit card, I had to change my account status (I don't exactly recall, but it seems like it was a change from personal to vendor or something like that.) I've only sold on ebay 5 or 6 times total in 10+ years.
Anytime I would sell on ebay and someone paid for something, paypal charged me AT LEAST one fee and most of the time TWO fees. They charged one fee because it was an ebay auction and they charged a second fee when the payer paid with credit card. It got fairly expensive, IMO.
Once I started MSing, I received lots of paypal payments with no issues. But I do recall one company paying and I was charged a fee, but I don't recall which company as it only happened one time. I figured the company had paid using a credit card or something.
Anyway, you do have to be careful with PayPal. They'll ding you just like every other bank if you aren't careful.