Fencing parts versus labor cost

[Kyrstin Szewczyk]

A neighbor next to my rental property has a dog. One of their chickens got into our property’s yard. Our tenant has a dog and is rightfully afraid of the chickens getting in and their dog attacking and or the neighbors dog getting in. 
The neighbor is offering to build the fence if we pay materials. Is this a fair deal? We haven’t bought a ton of lumber or had to pay a contractor recently to know where things are at other than that everything is expensive. 

Obviously, the most fair would be to share expenses and labor, except we do not have time until at least mid July to work on it. 

The fence is technically on our property probably, but he is the one that needs to contain his animals (the fence is adequate for our long term tenant’s dog to stay contained). Of course we also want to maintain good relations with neighbors but don’t want to get caught with a huge bill.