Yeah, I've seen a lot of great options for OOB access: 1) At carrier hotels, wifi (heh) 2) Cellular modems (ideal for branch offices; a lot of datacenters have bad cell coverage inside the racks/cabinets/floor though) 3) Cross-connect (in places with free/cheap cross connects) to someone you don't use for transit. Can be mutual 4) Some facilities give you an OOB network, although this often has issues (if you buy transit from them, it's possible your outage is due to something going wrong with them, and it might take out your OOB access)

I'm looking at the Verizon Private-IP thing (an outsourced private network over Verizon's cell infrastructure) for OOB management of lots of CPE; the cost per device per month is low, and then you pay for bandwidth across all of them. Makes initial provisioning easier, plus ongoing monitoring/maintenance.