TJ Maxx & Ross Dress for Less often sells EK Success & Martha Stewart punches for $3-$5 a piece where I live. Stock is hit or miss of course, but I've gotten 5 nice ones between the 2 stores. I hear Marshall's and Tuesday Morning sometimes has them also. I have also had good luck with local Stampin' Up demonstrators that sell their retired used punches for a good price. About a month ago, 3 local demonstrators joined forces and had a retired items yard sale. That was fabulous. I regularly see ads on my local Craigslist for Stampin' Up items, including punches. If your Craigslist is robust like Portland's is, it would not hurt to place an ad saying you're interested in buying used punches. Sometimes people don't try to sell stuff like that because they think no one would want it. (Wrong!
Also, if you have a place like this
where you live, you might find some interesting stuff. I've seen punches there, even got a dragonfly punch, and the store here in Portland has the biggest selection of used (and some not ever used) Stampin' Up stamps I have ever seen.