It is not that hard casting either. I would suggest a Lee mold because with a small amount of prep to clean them and maybe smoke them, and you are going to be turning out stuff you can use. Of note, the Lee 356-125-2R has been very good for me at 50 yards, I have not tried taking it our farther yet. Accurate and simple to cast. Out of pure lead it will probably drop right around the size you need or .357. Of the molds that I've bought, the Lee stuff always seems to be easier to get goin. Only exception is the Accurate Molds .510 that I bought, it is definitely a cut above but it also costs 4 or 5 times more money.
I suggest getting 2 cavity molds. I find this to be the right amount of weight vs production. I have a 4 cavity Lyman steel mold, and it is just heavy, especially when you get the 4 155 grain cavities filled. I can turn out ammo with it, but I do not enjoy it as much as using the single cavity hollow point Lyman steel mold of similar design. The lighter aluminum molds with only 2 cavities are easy to use and I don't get fatigued using them. Part of this is getting older and getting joint issue, part of it is hand strength which seems to have gone away in the last couple of years. It also holds in my non-dominant hand which also doesn't help me. But I feel I can turn out just as much ammo from a 2 cavity mold as I can with that 4 cavity. I'm actually thinking about buying the 2 cavity version of that Lyman and selling the 4 cavity. I'll take a loss but I just don't like using that heavy mold as much as others.
Back to Lee, there is the above 125 grain, there is a 102 grain of similar design that I may buy, and there are a couple up in the 150 grain sizes that I may look at before the end of summer. Some of this depends on testing of the Lyman mentioned and a small NOE design that is 88 to 84 grains depending on the size of the hollow point. If both the Lyamn and the NOE work well, then I'm done experimenting.
Lube or powder coat what you cast, same for what you buy if they don't come lubed or coated. The pressures from these larger bores seems to cause more leading than smaller bores, so they need a little help. I have a lube I need to try, but so far powder coating and a decent barrel seems to be working really well.