Who wants to collect something that is, in my opinion, very rare? However, you can buy these rarities for only a few dollars. And in some cases, you might be able to ferret them out of garbage cans.
The USPS continues to produce paid-reply postal cards. Why, I donít know. There must be some demand for them (beyond sales to stamp collectors). When is the last time you saw a non-philatelic, postally used paid-reply postal card? I bet itís been 20+ years.
When I was President of the local fire department, I would get a few of these per year from neighboring fire departments that were having a parade. You sent back the reply card if you were coming. Luckily, my fire department was not interested into going to parades, so I was able to keep a few of these used, paid-reply cards intact. I still have them.
Are they rare? I think so. Valuable? Not really. Like most things in stamps, demand is king and there is low demand for postally used paid-reply postal cards. Hereís an opportunity for you to start a collection of something that is rare, but itís not going to break your bank account.