PFSense on a cheapish high clockspeed server will easily get there. Total cost about a grand, a bit more if you want to use a low power no fan solution.

Oh man, I've been wanting to pick one of those routers up for some time. What did licensing cost you for your SRX 320?

I doubt they cost $3 per month though.

a pcengines apu does just fine, you'll get 900mbps+ easily with ipsec