photo: the internet
Many of my own shoe trees were also purchased at thrift shops, but they are worth buying new. They can be madly expensive, but they don't have to be. Best price I found online was $15.99 at Sierra Trading Post, plus $5.95 shipping. Not bad. But I recently discovered some fine ones not unlike those pictured above at Target for $9.99. At that price, I'd have bought a half dozen pair, but they only had one left. Best keep my eyes peeled next time I'm forced into such a place. Woodlore has a lot to choose from, in a variety of types, starting at $19.95. I might try them next.
Cedar shoe tress are worth every penny.