SBS has VPN capability built in. It seems like a waste to get hardware VPN for just 1 session. However, if you must have hardware VPN,
[u]this Cisco Small Business RV042 VPN Router [/u] should do the job. This will give you a hardware firewall, VPN, and replace your old router.
P.S.: There is an older version, the RVS4000, however, I won't recommend that as it's reached EOL which means no support. Also, there are several bad reviews.