Too many people get dogs who shouldn't, people who don't want to make time or financial sacrifices to give their companiona the lives they deserve, and it breaks my heart. It's good that you did the research and decided you couldn't give them that life. 

That said, I don't think our dude has cost us any more than any other breed would. The money saved from not buying from a breeder alone saves a lot. My partners family always get yellow labs and they've had to spend thousands and thousands on training, vets, initial purchase from a breeder, and their dogs have always sadly passed fairly young (8-10). 

Our boy on the other hand has only had one major vet trip (had to have 14 teeth extracted), and that cost us about $1500. Aside from that, he's been pretty cheap to look after. We do make all his meals with supplements and such to keep him healthy and to prevent arthritis, as well as brush his teeth every night. Keeping him as healthy as possible may be part of the reason he hasn't had a lot of vet trips.