I am trying to find a solution to a redundancy problem. I a running a
server which requires high availability. I currently have the server
running on a fractional T-1 line, but need wan over wan redundancy. 
Cable modem service is not available in our building and Cablevision
wants almost $10,000 to bring cable into the building. Are there any
other reasonable options that would provide guaranteed uptime?  We are
a small business, and cannot afford a $1,000 month solution. This
service would only be used on the occasion that the T-1 were to fail,
or could be used at all times for load balancing.  Any
suggestions?   This is in Spring Valley, NY, 10977.
TIA.

Have you looked into business class SDSL or even satellite?