I have been using www.mycheckfree.com for a few years to pay my utility bills online. I just found out you can buy and sell using check free too.
It has been reliable for me when paying bills online. I trust this site and have just signed to accept auction payments.

Sellers it is about the same fees as Paypal ( a few cents less maybe) The seller sign in is different.
Pay for auctions
https://retailpayments.checkfree.com/capbuyerconsole/logon.aspx
Sellers sign up or check it out !
https://retailpayments.checkfree.com/CAPConsole/Logon.aspx