But that's different -- those are businesses. They want your business, and in order to get your business, they're offering you the convenience of paying by credit card. For that convenience, they have to work that in to their overhead. (Notice I do not say that they eat the cost -- businesses never eat the cost, otherwise they wouldn't be a business -- businesses pass costs to the customer.) As the occasional seller of goods, I don't care how I get the money, so I'll stick with money orders, myself. It's up to PayPal to raise those limits, though, not you. So though it may not be an issue with you, it is an issue with the infrequent user who occasionally goes over his limit. Have they ever raised your limit? I didn't think so. I've never heard of them raising their limit for anyone.
(And if they did raise your limit, I'm curious how you went about doing that, because that would be the exception, not the rule, from everyone I've heard.)