Won’t share a mini cut with him then

My neighbor and I share a shed.

Technically we have our own entrances and separate spaces.

However, someone built my shed, and then built the shed next door using a single of my exterior walls. It is particularly discouraging because when replaces are made, usually I have to work with my neighbor. When I wanted to replace my roof, technically it stems into a portion of his shed. I had to get him to agree on a new roof and the cost of it. He is super cheap and so I ended up only doing half the roof; Recently the topic of Heating and A/C came up. I want to add a ductless mini cut to my shed. The cost is so overpriced. I found you can hook up several indoor air handlers to a single outdoor air compressor, so I suggested that my neighbor cut the cost. Both of us each get our own air handler and thermostat, our thermostat settings won’t affect a single other. Both of us just share the initial cost of the Heating and A/C and replacement. The guy then started talking about a friend that had a Heating and A/C system and could install it. It wasn’t a real Heating and A/C brand and the guy wasn’t a Heating and A/C contractor. So I am dropping the subject. I suppose I am just going to need to buy the overpriced Heating and A/C and let my neighbors’ tools rust in the high humidity. It’s his own fault. If he was willing to spend a little currency he could have enjoyable temperature control for half of what it should be.