Are you U.S.-based or international in origin?
It is readily possible to find U.S. merchant processors with low or even free setups as well as low monthly fees along with very competitive discount rates... so I'm not sure as to your motivation for wanting to pay a higher % is?
In almost every case, you will be much better served with a more mainstream merchant account. The only exception is if you are only processing a few sales sporadically in which case a 3rd party processing account might be better for you.
Now, if you are based outside of the U.S., your options are a little bit more limited but you can probably talk with a company like PaySystems, 2CO or even use PayPal if that is the case.