A LEE Classic Cast Iron single stage press (If you can find one?) will be sufficient to load your 1st 4 to 5 thousand 357 Magnum reloads. Buy the Hornady LnL conversion bushing kit and a good set of 38/357 carbide dies (Hornady, RCBS, etc.) or the LEE 4 Die set and you will be good to go.

A good scale and initially individually weighing each load can eliminate the under & over powder charge horrors (the dreaded Squibs & the KABOOMs!) that seem to be a never-ending subject on this forum. A cartridge case gauge is a worthwhile investment as well.

You will be able to load various different types of bullets before too long, once you master the correct expansion and crimp functions. Unless you shoot many hundreds of rounds on a weekly basis your production rate will be more than sufficient and you will eventually find reloading in 50-100-150 increments pretty easy and quite satisfying.

Cheers!

P.S. Hopefully you will (of course!) not be shooting ANY dreaded 38 Specials (because the "crud ring will destroy the barrel"!) and are not shooting one of those "frail K-frames" whose forcing cone will surely self-destruct from flame-cutting after only a few (thousand?) rounds...?

P.P.S. After checking on the net perhaps the RCBS Rock Chucker Supreme is a more available solution: Natchess actually has them now and they are on sale... Maybe even amazon with FREE DELIVERY?