Question: I'm moving a couple of servers to a colo and was wondering what you would recommend for a hardware firewall to sit in front of them? Is it fine to just get the cheapest Cisco/Fortigate/Juniper/whatever firewall? I don't need anything fancy, pretty much just port forwarding.

Answer: 
I would not get the cheapest firewall. You need to look at your requirements such as throughput, active connections, security, vpn requirements and more. If it needs to be cheap I would recommend setting up a separate linux box as the firewall using iptables. If there is budget for a firewall but you need something small consider the cisco asa 5505(smaller than 1U), or if you need something with more requirements consider the 5510 or 5520 which are rack mountable. The cisco firewalls have a gui interface and after initial setup can be relatively easy to manage.
Alternatively - get a Mikrotik RB1100 and see how far it lasts (50mbit for smallish packets was on the table by someone running game servers).

It is CHEAP and has a TON of features in RouterOS. Uses very little power, too.

Then later you can upgrade to something more powerfull if needed. Again, the RB1100 is CHEAP to start with.