You can buy the "spring bronze weatherstripping" variety at kilianhardware.com. Those are the search words.

I also get spring bronze at my local, old-fashioned hardware store.

It's v-shaped, and is applied with little nails. It's not self-adhesive or vinyl, but it lasts a long time. We prefer it to the vinyl type.

Check TrueValue. They may have it. I'm in Boston too.

Thanks for responding. I found it on True value and Amazon.

Simplyconserve.com has the narrow v-strip. The wider v-strip (1 3/8") is available from amconservationgroup.com but only in a case of 100. I've used the wider strip when it was still available in smaller quantities, and it's been great on my old restored sash windows. Highly recommended.