Cheap plant labels are everywhere, you just need to look around. Most of them will be free. Have you ever seen mini-blinds discarded by a trash can? Mini-blinds are replaced often due to animal damage and people just being too lazy to clean them. They can be cut into hundreds of 6 -8 inch plant markers. Color doesn’t really matter, but usually you will find them in white or beige and those are perfect.
Whenever you drive through a take-out food place, they are happy to put plastic silverware in your bag. Plastic flatware is also cheap to buy. Watch for sales at party supply stores. When they have 50% off sales, you can get boxes of colorful plastic knives for very little. While you can use spoons and forks also, knives are the most useful and can be purchased separately. The plastic knives tend to stay clean since they have such a slick surface.
Popsicle sticks. If you or your children eat popsicles or fudgesicles, you have your own reoccurring supply. Boxes of popsicle sticks can be purchased from a craft sale. They tend to get dirty and don’t hold up forever like plastic knives, but they work well.
Flat rocks. Do you have a source for flat rocks? These can be cleaned and written on with a marker. Some people even paint on them. The only con, is that they need to be kept up out of the dirt or a rain will coat them with mud and make them harder to find and read. A bed with mulch, such as a rose bush bed, would be an idle place for a rock planting marker.
If you really want to get creative, you can use molding clay to make markers in different shapes. You can roll out the clay then use cookie cutters to make it into shapes. If you live in an area like I used to live in Oklahoma, you can dig your own clay, then mold your markers, let dry, and you have your labels.
Please comment on any other label ideas you have.