If you have a cordless drill, you don't need a winder. Mandrels are transfer punches and aluminum knitting needles - if you use both, you will have both fractions and mm sizes.
I teach chain maille workshops and make chains to sell; I've cut at
least 10 pounds of (copper and sterling), rings over the last couple of
years using my old, dirty, cordless Makita drill, flexshaft, transfer
punch/knitting needle mandrels and Dave Aren's Koil Kutter. I haven't used any of the other generic jump ring cutting systems, but I've read some people are unhappy with the Pepe version.
I have used the standard Jumpringer and the Koil Kutter with my Foredom; the main difference is the standard Jumpringer has an aluminum blade cover and, the Koil Kutter's blade cover is pvc. The end result is exactly the same, perfectly flush cut rings with no burs. You can buy a long coil holder and long mandrels for both systems, the Jumpringer has an additionally set of mandrels and coil holder you can buy for different shaped rings (diamond, square, oval) which is not available for the Koil Kutter. Also, there is a new Jumpringer than can cut all metals - platinum, steel & aluminum, in addition to gold, copper, silver.
I only cut copper, gold and silver, so the new Jumpringer system is of no interest to me. You can buy the Koil Kutter for under $100 from Dave Arens.