I made up excatly this using 50mm aluminium tubing and some dinghy spinnaker pole ends made by Holt-Allen. I happened to have the tubing - it was an old junior windsurfer mast - but it should be available pretty easily from metal suppliers (Yellow Pages?). The pole ends were Holt Allen part number HA4331. Cost approx £25 each. Works a treat. I use it for poling out a cruising chute.
Compass do a pole that extends up to 2.5m.It is £79.95 item no 207108 in their catalogue.You can get to their website via this website or www.compass24.com