I've been checking into pet insurance also. There is one that is only about $18 per month for each dog. It has a $100 deductible, covers everything but routine visits which is an optional add on tho, with a $2,500 limit per incident, no annual limits, $42,500 lifetime limit. This was the SPCA best for 2008 insurance company.
http://www.petsbest.com/plans/default.aspx