The cheap exchanger on Craigslist disappeared, I ended up buying a 155K btu stainless steel pool exchanger online- $175, 2 rolls of 100' 3/4" hose, and a utility pump.
Had a Taco 007 in the basement from a job I did, plumbed that into my OWB to run the loop to the pool exchanger, put that in a wooden case under the boiler. Put 2 unions in to disconnect and store for the winter. 2 quick disconnects for the garden hose and I am off and running.
So far, 6 degree drop in the loop to the heat exchanger. Raised the heat if the pool 2 degrees in an hour and a half. Overall pleased with the whole setup. Thanks for the ideas. Total investment: $300.