Tax Rate Updates

Would anyone have good advice on the best most economical way to load and keep the tax rates in eBTax updated. We own the module, but have only maintained a single tax rate for all locations. We would like to start using more of the functionality, but the big drawback for us was cost we were quoted 300,000 to 400.000 annually by some of the tax services. We are primarily a US based company and by and large all of our business is conducted in the US.