What type of VPN, and for what use? Do you want to VPN into your home machines from anywhere?
I use IPCop as a firewall (free) and also have it setup as a free VPN server. (OpenVPN) Free...
IPCop is basically a small basic Linux install running IPTables with a nice front end, on an old laptop with 2 NIC's.
Everything else is free (as is the old laptop, work buys me one every 3 years, so I have the old ones lying around).