If you can't get your hands on the different elements needed to make Mel's Mix, or you're looking for a ready-mixed potting medium, there are a few alternatives out there that make a pretty good substitute.
According to Tony, you can combine compost with coconut coir as a sustainable alternative to peat moss, and perlite can work well instead of vermiculite. 'Again, the key is creating a soil mix that balances drainage, moisture retention, and nutrient richness,' he says. Although it may not have the exact characteristics of Mel's Mix, it still offers the same key benefits.