It's not odd that an art teacher would be a collector of old art materials. My house is decorated with art and art supplies along with other eclectic items I treasure. I've gotten many of these art items from family members, friends and even former students, along with purchasing a few myself. Most people don't notice the old box of chalk or jar of dried up paint as being something anyone would want to have.
I haven't added to my collection for a while. Have you ever collected something and at some point it's too easy to accumulate and it's not as much fun anymore. Of course, once I see that unique piece I'll be all excited again!