Hi,
here's another link you might want to take a look at. I chose this product
for a class assignment, so I cannot give you a recommendation, but it seems to have
versatility and features redundancy as well.

http://www.linksys.com/products/prod...id=34&prid=589

The router comes in at under $250.- a piece, if you shop around. It fits in well
with xDSL. Best would be to use SDSL with a Service Level Agreement. Many
ISP's provide this service these days. The plans are flexible and inexpensive.
A 256K up/down service should put you in the $ 150.- monthly fee range,
but you may not even need that much bandwidth. You can always upgrade the service.

Some negative issues in comparison to traditional Frame Relay or ISDN may be that
you'll have to deal with possible oversubscription of the service, scheduled maintenance outages,
and last but not least, the exposure to the internet.
This raises the issue of hidden costs associated with maintaining a security policy
(ie. Updates, Wireless Access if installed, etc), AV software, tech support( configuration and maintenance).
But a gateway to gateway VPN config should be relatively easy to set up.