Are the others peat free? Most bagged mixes contain peat.

I too believe most potting mixes also contain peat. One should read the package for ingredients. That said, I have seen some bagged mixes which don't list them at all, so I don't buy those.

I suspect most potting mixes DO have peat in them, especially since they'd be for houseplants which can tolerate it much better than succulents can.

Ideally one should avoid mixes w/ moisture control agents (you want to decide about watering, not the mix or its maker who knows nothing about your growing conditions.)

Same w/ fertilizer, its timing & frequency should be in the grower's control, not that of the mix distributor /nursery.

Personally, I would stay with the C&S mix. If you buy regular soil, you'll have to mix much more perlite in it to achieve the fast draining mix that C&S like. If you do a search on here for potting mediums or potting mixes, you'll get a lot of information and see that most of us are using an almost, if not entirely, soil-less mix. My own consists of pine bark (sold as soil pep), perlite and crushed granite (sold as chicken grit).
The reason you were told to mix perlite in with the peat moss is this: if you were to use the C&S mix straight, eventually the peat would dry to a hard clump around the root ball and become hydrophobic, meaning that it would never reabsorb water and allow water to the roots. The perlite will mix in with the peat and create enough spaces around the root ball and throughout the mix that some water will be able to reach the roots. How much water depends on how much perlite you mix in.

Nancy

Thanks for the help guys! I will see if I can find anything that has less peat, otherwise I will keep using C&S mix for now. Is it a good idea to mix horticultural sand? Is that the same as granite? The reason I ask is because I'm afraid that from all the comments on how difficult it is to grow lithops or even other mesembs, I wondered if I need to come up with a different soil mix to have a better success rate!

No, no sand...unless the sand particles are about 1/8 of an inch in diameter, in which case they'd more rightly be called a fine gravel/grit.

Josh