| I found a pkg of 50 of these at my local thrift store for 50cents. You hang the tag on a wine bottle with the circular cut out on the tag. They are a shiny tag about 1&1/2"x3" from Epic products. www.epicgifts.com
I cut out the very bottom and have two legs to insert into the soil. They seem to hold up with markers or overhead transparency pens and go into the soil about an inch.
Wish I had seen more there but I will make use of the 50 since I am repotting some WS containers as well as the next round of seeds under lights. | 
