Bale of peat moss = $13 for 6 cuft
Bag of perlite = $20 for 3.5 cuft
Compost from hardware store = $8 for 2 cuft.
16lb bag Basalt = $30 from BuildASoil with free shipping
5-5-5 Dr Earth = $15 for a 5lb bag.
Making your own batch of dank soil on the cheap? Priceless.
Seriously though,
1 bale of peat moss, 2 bags perlite, 2 bags compost, basalt, + Dr Earth mix = ~$115 for 16 cuft (120 gallons) of soil.
Same amount of money will net you 9 cuft of FFOF, or equivalent.
One time cost for me as I run no-till, just plant new plants in the same pots, top dress with your preferred organic amendment mix, cover that with compost. Done deal.
That 16 cuft of soil will last you multiple years before it fully decomposes, then it becomes your compost input for your next batch of soil.
Only requires maintenance costs in the form of organic amendment mixes and compost.