Redundant DSL Connections

Anybody know of a particular device that will let you have 2 DSL connections from 2 different DSL providers so that if one goes down the system automatically switches to the other? I see a perfect product at www.fatpipesinc.com but the base price is $9,400 and I need this for many small business networks. Ideally, one NIC in proxy server connects to this device which has two network connections – one for each DSL router/modem.

Thanks for ideas!!!