One male can make in one testicle in one day enough sperm to populate the world. . ."half-neutering" is the oddest thing I've ever heard of. It certainly won't make fewer kittens, it won't prevent objectionable male behaviors or odors, and there is no reason to take the risk of putting a cat under anesthetic if you aren't doing anything useful. Any vet who would take someone's money for that should lose his license.
Besides that, if your cats are going to new homes, they should be fully neutered anyway. This will make it more likely that their new owners will be happy with them and they'll stay in their new home (less chance of spraying), and there's no reason for their new owners (or anyone!) to be breeding moggies, accidentally or on purpose (even if they are good-looking). There are plenty of cats to go around already, we don't need more of them being created!
I can hardly object to people having a lot of cats (having 20 myself. . .), but I do firmly believe that they all need to spayed and neutered (fully!), have at least their kitten shots, be kept as flea-free as possible, fed a reasonably decent food, and be de-wormed on a regular basis, besides keeping a reasonable level of cleanliness. If that minimum of care cannot be maintained, then that means that person has too many cats to care for properly and something should be done to remove them from that home.
I have had several of my cats spayed/neutered at a low-cost clinic. They do fine work, and also do vaccinations and testing (not all clinics do all that but it's not rare). If I can find a low-cost clinic out here in the boonies, I'm sure you can find one in California. As stated before, the other CA members here can find a low-cost program for you if you're having trouble finding a suitable place.
If I hadn't been able to find a low-cost option, I would have kept the males and females separate and had one done at a time as I saved up the money---I probably could afford to do one a month. Slow progress is still progress! Even if money is tight, there's always something we could cut back on in order to save up for something.
It's great that you've managed to keep your females away from the males for so long, it's really not something that can be maintained long-term. Sooner or later a male will get to the females and father a few litters. Plus, if females cycle too long without breeding, they are almost certain to get pyo or another reproductive problem (even if they are "low-estrus". . .maybe more so. Low estrus isn't normal and could signal the beginnings of some health issues). Spaying them is for their own benefit.
I do have to agree that Foxtail doesn't look terribly healthy

. Perhaps you can have your vet look him over. He seems to have a runny nose and his fur looks like he hasn't been grooming himself (many cats stop grooming when they're sick). He also seems to have a herpes infection in his eyes (which is very common, especially in multi-cat homes). . .l-lysine powder is very good for this. You can buy a nice big bottle of it from Amazon for less than $20. It's done wonders for my cats.
I counted 44! Is that all of them or do you have more than that who aren't neutered or spayed/low-estrus? I may catch up someday

.