+1 on the Campmor ponchos. They have good quality at a reasonable price. Also check out REI, who has good ponchos in various sizes, with snaps and grommets aplenty, at comparable prices to Campmor.
MilSurp ponchos are generally heavier than "backpacker" ponchos, but also more durable, and usually a little cheaper.
As for insulation, check out the local fabric store, buy some fleece yardage of whatever weight you feel needed for your climate and intended uses, and make a liner for whatever poncho you have. It's easy to put snaps, grommets or whatever along the edges, even tie tapes.
Just some thoughts.