Thought I would share this; I built a DIY vinyl cutting head for my MDF router table by using a needle holder from the roland Stika cutter and making my own insert out of aluminum.
Roland blade holder: Cheap chinese knockoff (perhaps?) on ebay:
http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWNX:IT
The project overall was very simple and works perfectly.
The holder is a simple aluminum rod bored out to allow the spring (ball point pen) and retainer (PC motherboard standoff) to rest and compress when the needle pushes up against any uneveness of the material. This allows the needle to float over the surface with an even pressure.
total price: 17.00
Edit: The tool fits into a 1/2" collet.