Actually you can get unloaded cabs. I have a friend that builds amps and cabinets. www.headstrongamps.com
I'm also working on building some cabs for myself, and some friends. A buddy at work has a wood working shop, and wants to build some stuff. I'd like to build some with maybe 2 12's, and a 15. I played a Rivera that was set up like that, and it sounded awesome.
SwedeNuck's Earcandy 2x12 is sick, but I can't seem to find any info on them *EDIT: **** I feel smart, earcandycabs.com* Last time I checked, Avatar doesn't ship to Canada. I'll check out Splawn.