Internet Merchant Account Providers?

Hi,

I'm setting up an e-commerce solution with a custom shopping cart and
Verisign's Pay FLow Link at the gateway.

My client, however, is complaining about the terms of his current
Internet Merchant Account and doesn't like Verisign's recommended
solution, either. His bank does not offer anything.

Does anyone know of any solid and inexpensive IMA providers? And how
compatible are different IMA's with different gateway solutions? I have
to admit, I'm a little fuzzy in this arena. Are IMAs standardized so
that an established gateway like Verisign's will be able to connect to
any of them?

Thanks if you have any suggestions.