Cheap SONET mux recommendations

I'm looking for recommendations for a small, cheap SONET ADM for our labs. It doesn't have to be fancy, just basic ADM and TDM mux functionality -- we don't care about NEBS, redundancy, remote management, cabling simplicity, power etc.

Our ideal system would take in a channelized OC3/STM-1 and drop out CT3 / CE3 and T1 / E1 trunks. We're open to having a cheap OC3/STM-1 to CT3/CE3 ADM, and then using an M13 to demux the CT3/CE3, if that's a better combination.

Replies off-list appreciated (I can summarize if there is interest).