If you already have the brass and really want to go cheap, pick up a case of surplus 7.62x39 ammo, pull the bullets and powder.
Then, scrap the surplus cases.
Weigh several charges of the powder in the surplus cases, before dumping it into a container. Take an average of those weights for future reference.
Put all of the pulled bullets into a container.
Usually, the Chinese surplus has very consistent weights of ball powder and bullets. Their powder burns dirty but it's very consistent in its burn rate.
Unlike the smaller, shorter 100 or 110 grain "plinker" bullets used for the M1 Carbine and 7.62x25 Tokarev, the 125 grain fmj, surplus bullets will usually shoot very well in most 308 bores with a 1-12 twist rate.
YES, I know the surplus bullets are .310 in diameter, instead of .308 in diameter.
NO, using them won't blow up your rifle.
As for the powder, you can use it by setting up your powder throw or electronic dispenser etc to the average weight you calculated previously. The powder is very similar to BLC2 in burn rate.
This will give you loads generating appx 2400 fps from a 22 in bbl.
If you want more velocity, carefully increase the powder charge. The only drawback is that you will have bullets left over.
Cost depends on how much you pay for the surplus ammo, but it's usually under thirty cents per shot.
Don't expect sub moa results. However one moa results are often the end result, especially in bbls with 1-15 twist rates.
1-10 twist rates seem to shoot as well as 1-12.
I shoot these rounds out of two rifles I have on hand. Both are Rem 700 SA rifles.
One has been fitted with a Remington, fluted, factory take off bbl, 25 inches long, with a 1-12 twist rate. It shoots these cheap loads into slightly over one moa all the way out to 200 yards, which is about maximum practical range for this load.
The other is my last Hunter Bench Rest rifle, put into a more practical stock for field use, with a 1-15 twist rate. This rifle is a true one moa average group shooter with these bullets. Likely because of the short throated chamber, cut to very tight tolerances.
Hope this helps