Yeah I can see why they are not upfront about there prices, I use paypal to handle online payments through my website and there charges come out at around 54p for a £10 payment. I look at like I would pay this in petrol, driving back out to the customer to try and collect again, it is roughly the charge I pay for cheques and it doesn't waste any of my time.
If nobody pays online one month then I dont have to pay any paypal charges. I would have to take over £220 in online payments each month for this method to be cheaper than paypal, and it is just not used that often. We do evening collections, so get around 98% of people in anyway, this really is only to catch the ones that fall through the net.
Plus I wouldn't want a large number of my customers paying online, I make more money if they pay me in cash. If all my customers paid online, I would really have to rethink my pricing structure, to account for a percent of my pie going to using this type of service.