I bought mine from West Marine. They are light weight come with stick pads not that expensive and last a long time. Easy to see red - green.
Why buy when you can build? Specially coming from you, im disappointed. LOL j/k
Yeah the vinyl part will be the sticky part and the tell tales will be used on the leach of the main. Replacing them every month wont be a problem.
I remembered this thread while sailing this weekend.. and i think the length is more like 12" (both mid sail and leach tell tails).
I have put leach tails on before and they had 2 triangle shaped stickies so you could get the tell-tail right at the leach... and stick it to both sides of the sail.
PS ... I PERSONALLY wouldn't want to have to change my tell-tails often, nor would i want to be putting sticky tape on, and ripping it off my mylar with any frequesncy...