One of my characters got it into his head to create his own private encrypted WAN in the area around his base of operations. How much does it cost for a high-rating wireless router? What's the Availability? What are my options if my Availability/funds are limited? Where are the rules for pure routers?

All you need is a "comm unit" with "Signal 4". That will give it a range of 1km. Add the Encrypt program to all of your devices and you've got a private encrypted WAN.

If you want to just purchase the device as a repeater, and not let it have any other functionality, I might let you purchase one for 1/2 price, but you really want a full system so that you can run Analyze, FIREWALL, and maybe some ICE on there to watch the network for intruders. It's only 6k for a trans avalon with the 2nd best OS, what's the issue?

the issue is that it's a ganger campaign, each BP gives 2500 nuyen, max 20 BPs spent, and he has 310 BP total (and he also has to make a hacker/rigger character with his resources to boot =P )

since you're asking

the bad news is, there is nothing 'official' that does that, and the GMs tend not to like houseruling anything at all...

Even worse, he's restricted to availability 6. Six! Signal 3 hardware? Availability eight!

Makes you almost want to cry.

Cheapest drone you can find, Limited mobility, Retrains unit, and Satellite uplink Mods, You now have a router.

well yeah, but the commlinks themselves have no availability rating, so you can buy several =P