"I haven't priced out your parts list, but I would be surprised if it comes to less than $80."

No it wouldn't be that cheap.

"I need a total of 20 gigabit LAN ports for my network. Currently, I have two 8 port gigabit switches, and 4 10/100 ports on my current BEFSX41 router. I want to upgrade the router for open vpn, and gigabit speeds. So the router is also a switch"

I assume with DD-WRT that the router has the capability to perform traffic shaping and control the built-in hardware ports. How good of a job does DD-WRT do with this? What about bonding? This may not be needed now, but without knowing what the bandwidth usage is for the 20 LAN ports having that as an option may be something to condsider.

"What is the advantage of running the whole thing virtualized?"

Not sure, although having the ability to move the router configuration quickly to another system might be an advantage.

James