You could get a P60 host that is designed to run on 18650's, plus an appropriate p60 drop-in (i.e., LED module) for very little money. For an inexpensive host, consider the Solarforce L2, or L2P, (or one of the L2M's that comes with the extender that allows it to take two 16340's or one 18650). I believe all the Solarforce hosts can usually be found (on ebay or Lighthound) for less than $20 shipped. You can get a cheap 5 mode XPG R5 drop-in from DX for about $14 shipped. I have an L2P (with a super nice matte black HAIII finish) set up that way and it is a very bright and very nice quality piece of kit for about $35 total (not counting the 18650 I run it on).
If you want to spend more money, you can get more expensive drop-ins such as a custom one by MP vendor "Nailbender" or a Malkoff, or various others. The Solarforces though are amazing quality hosts for the money.
