Hi opsoff1,
Many people re-use old automotive serpentine belts for their lathes. They are basically free.
One other advantage over an endless belt, is that you do NOT have to disassemble the lathe spindle to install/replace.
(Although that's often a good time to inspect the bearings/bushings.)
On my first attempt I did similar to Jim above and tried a scarf joint. Mine was only tapered about two inches (done on a bench sander) and then stitched. The joint, although flat, seemed to be stiffer than the rest of the belt and I was never able to stop the slight "thump" as it went over the pulleys. It was worse with the smaller pulley steps. Also, I ran that one with the flat side against the pulleys and eventually the stitching cord wore thru.
More recently, I tried a simple butt joint based on a recommendation from this site. It has turned out to show no problems, however it's only a few months old, so not many miles on it. The good news is that I've already got another old belt waiting in case I need it. This one I'm running with the belt ribs against the pulleys and the stitches are done in the valleys so the cord is not abrading.
Here's what I did, the belt front (outside)
...and the back:
It was sewn with the two ends tight together, but with the stretch in the cord it now has a slight gap. That does not seem to be a problem. I used a nylon cord:
http://www.leevalley.com/en/garden/page.aspx?p=32009&cat=2,51553,32009
and a sewing awl like this:
http://www.leevalley.com/en/wood/page.aspx?p=50700&cat=1,43456,50700
Be sure to release tension on the belt when the lathe is not in use.
-brino