I've seen older f5's on ebay for about $500 for a pair. I've heard they work great for load balancing, but I'm trying to figure out what the ongoing costs for them are. Does anyone know what kind of licensing and/or subscription you need to get for these things to make sure the firmware is current? Or is there even a license required? Can I just buy for the $500, set up, and go?
I can tell you for sure that you would have to pay for license upgrades based on capacity of some LB features. For example, a company I worked for have upgraded license several times to expand simultaneous SSL sessions capacity of LB setup from 25 to 50 and later to 100 (used for HTTPS offloading).
Unfortunately, I'm not sure about F5's terms regarding basic OS upgrades, etc. Looks like their licensing policy is quite flexible and you'd better to consult with their sales representatives on that topic.
I suggest you call F5 and ask them.
They're easy to talk to and friendly, in my experience.
The software functions much like a Red Hat subscription - the support and current software version are a package deal. Typically the yearly subscription is not cheap costing upwards of several thousand dollars. That being said, you do get what you pay for. The support is world class as Brian mentioned (the sales guys as you discovered maybe not so much) and they will typically try to give you guidance even in areas that are not covered under the support contract. For example, they will give you one free support case if your contract is expired and will typically do their best to point you towards specific Apache changes or similar if they can and generally seem to try to go above and beyond.