OP, if you have a very decent press, which you do, how long have you had it and how much more procratinating are you going to do??
I'm not trying to diss you here. Just making an observation from your post.
You obviously don't have a mentor??
Something to keep in mind about hand loading, is that it requires a space to fix your RCBS Supreme press to.
You need a surface that is strong, without flex and doesn't move around while going through the motions required to size your cases.
Your press is likely the most expensive component of what is required to start and it's a great start, well above some of the other offerings out there.
You can pick up an electronic "MTM" scale for around $60 and IMHO, a scale is a must have. Most powders and the loads for different cartridges are available online and the 308win has a huge following with all sorts of loads and advice.
Then you will need chamfering tools, for primer pockets, and case mouths. If you have a hand drill, you can purchase bits that will do the job well for both inside and outside neck chamfering to remove burrs etc for less than $10 for the set. None of this needs to be specifically labled for hand loading.
You will also need some way to lubricate your cartridges inside the necks and especially the outside of the cases properly.
There are all sorts of methods and lubes available, some are very cheap, most do the job well if you're careful
Hand loading is not for a LAZY individual or one that can't handle repetitious tasks that require constant attention.
As for having to load thousands of rounds to recoup costs, not so, if you do some due diligence and have the opportunity to join a local range, which you should do anyway, or can attend a couple of gun shows.
At the last gun show I went to, appx a month ago, there were a half dozen, excellent condition 308Win three die sets for sale and none of them were priced over $40, only one of them didn't have a shell head holder in the box.
308Win brass is one of the most common types available at most shows.
Powder, primers and bullets have gone way up in price over the last few years. That will be you major expense and difficulty in finding right now.
At today's prices, expect the cost of a round of 308 winchester, IF YOU ALREADY HAVE CASES, to be around $1.10 per round. This will be the approximate cost of your primers/bullets/powder. This is about 1/2 the cost or less than you can purchase loaded ammunition for.
Yes, there are "deals" to be had but they're mostly one offs, so don't let some nimrod try to influence you that they're available to everyone. I alway have to wonder about the person that will drive a hundred kliks, one way to ''save'' money on a box of bullets or primers or??????????