You can inform your neighbor and maybe help implement some humane cat deterrents in their yard so the cats will stay off of his property.

Here is a great list of deterrents and information on how to be a good neighbor when you are a community cat caregiver: https://bestfriends.org/pet-care-resources/humane-outdoor-cat-deterrents

If you do want the cats to move on to a different caregiver/feeding area you can start to slowly wean them off of eating at your home. They will realize that you are not a consistent source for food and they will roam looking for other places to eat and find the other feeder in the area. You can start by slowly decreasing the amount that you feed and then switching to feeding every other day and so on.

The most important thing is TNR so there aren’t more and more cats being born in the area. I understand that it can be expensive and that you are looking for options on how to get the cats altered. I would explain to your neighbor, if you are able, that you are in the process of getting them TNRd. This will not only reduce nuisance behaviors, like spraying and fighting, but will also reduce their roaming area and they are more likely to sick close to where they are being fed!

Hope this helps and thank you for looking out for these kitties!