In reply to TomBond:
I use A4 vinyl sheets found and bought on eBay for £3.50 for 5 sheets.
Each sheet can be cut into 150: 7cm x 6mm strips with a Stanley knife and ruler.
Using 2 strips give a unique tag as there are at least 2 dozens colours to choose from.
I got one sheet of orange, one purple and 3 sheets of clear to give my tags another Layer of protection. Most likely over kill.