I've. been loading for a number of handguns for going on 20yrs. I had all sorts of brass from several manufactures and used it over and over again. Some lasted a good while some didn't. Then I decided I wanted to standardize so I ordered 1K of each caliber from Starline.
Out of that, I have used probably 3-500 depending on caliber over the last decade or so, and at the rate I am going my grandkids will have new cases to work with when I am gone. In all that time I saw and even picked up some range brass depending on what it was and the condition. I have even since purchased several K of once fired 45ACP, thing is you never really know if it is truly once fired. I usually use it at the public range where if I loose it it's not an issue.
As for the primers, I was fortunate enough to have had plenty to get me through the Clinton admin as well as enough to last through both of the past issues with the new admin. There again I purchased some of the Wolf primers just to try out and I use them for around 80% of my loads.
As for molds, the Lee stuff gets a bad rep, but they are decent enough to produce quality bullets if you monitor what your doing. A good thermometer goes a LONG ways in keeping the lead at a certain temp range which the mold likes. I also have Lyman, RCBS and a couple of customs. As with a lot of things you get what you pay for. That said it's hard to beat a $40 Lee six cavity for production when you have the temp right. Even if you have to tweak it one way or another, it will produce.
My affliction now are MP molds. They are high quality usually in 4 cavity, and usually have several HP pin options. Are they for everyone, no, but if you find one in the caliber and bullet style your looking for, they will last and you have several options with them. Most other HP molds are either one cavity or two, and only in certain caliber or bullet styles. That is what put me on to the MP's. Thee is also NOE, (Night Owl Enterprises), NEI, Accurate, and a couple of others which also produce VERY fine molds.
If your contemplating casting your number one consideration should be securing enough lead to actually get into things. That IMO would be somewhere in the neighborhood of 500# pounds, with the ability to refresh your supply as you go. I say that due to the fact lead is getting harder and harder to come by. If you have no way to recoop your bullets, you will find yourself going through your supply pretty quickly.
