Like posted above its not pick buy and dump.
There is a little more to it than that.
I just started hand pouring for my self a few months ago. I got into it for about $200 to start.
That's going to the 99¢ store, buying some tupper wear containers, Walmart pirex cups and junk metal knives and Home Depot for plaster of Perris ($40 ish bucks all together) to start makeing molds.
Then I went and searched online for cheap but good supplies. Got 3 jars of glitter, 5 dye colors, 1gal of plastisol and an old microwave from my GFs garage (about $130 ish shipped) and some other small odds and ends to get pouring.
My first week was just junking supplies learning the dos and donts, how to mold and how to pour, still learning. But now I'm finally getting usable plastics.
I've done the math and am getting a standard 3.5" swim 2 color bait for about $0.28 a pop. That run $0.75 at my local shop. $0.40 for one color craw dads which run about $1.20 at my local shop.
So it's not dirt cheap to get into it, it's actually frustrating and confusing. But now I have it about down pat and am able to make what ever my mind can think of and customize my baits for me and my buddies. They aren't flawless but I'm not in it to sell, just fish my own baits and have fun doing it so my 98% sexy 2% ugly baits is good enough for the fish to bite. Cause let's face it, 90% of the fancy colors and looks of baits are for the fishermen, not the fish.
So if you have $200 to blow it's do able on a budget, if you want quality sellable baits expect around $400+ to get started.
So if you get into it, expect a ton of trial and error, wasted product and slightly less sexy baits but the fun and great feeling of making your own and doing what ever your heart desires.
The other reason aside from plaster of Paris being cheap and easy to work with, you can carve away and start with your favorite factory baits and get to customizing and mocking up your own custom baits and make changes on the fly to what features, ridges and bumps your bait has.
Where aluminum is buy what you get and $$, and silicone is $$ and not as easy to cut and mold for custom add ons.
Each way has its own pros and cons. GL and happy. Molding bro!