Looking for power metering equipment...

Preamble: We run a colocation center. We sell power to customers. Question: We are looking for something that sits in the PDUs or branch circuit-breaker distribution load centers, that, on a branch-circuit by branch-circuit basis, can monitor amperage, and be queried by SNMP. Considering there are several hundreds of circuits to be monitored, cheap and featureless (all we need is amperage via SNMP) is fine. Looked at things like Square-D PowerLogin stuff, but thats very pricey, and does about 30x what we need. Pointers? URLs? Experiences? Thanks.