I've never owned or operated a DSLAM before, but is there any reason why you couldn't get two of them, two phonelines, and two DSL modems to achieve a 6Mbps backhaul for the price of two phonelines and about $3k worth of equipment? Ebay has a few that are about $1000...
update: you can't buy lines that are direct from point to point.
Ashley, maestro of telecoms and more, says:
Check out thedry pairconcept, if you haven't already per your update. Basically it's what you wanted: a point to point pair of cables w/ no dial tone. Alarm companies used to use them all the time to have a direct line to monitor you house with. Cringely wrote about it back in 2001:
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