DIY is the answer and your wife needs to get over it. This appears to be mostly cosmetic. Not anywhere close to a water heater. And sorry, I call BS on eight years without a functioning water heater.
DH is professionally known as a Specialty Surfaces Specialist. He is a licensed painting contractor, but for his work he paints, er, coats Very Large Objects. Huge, even. I will show him your photos later today to seek his advice. I suspect some kind of flexible, waterproof sealant will buy you some time and save you a shitload of money for now. What's your climate like in winter? Also, I'm guessing this is only surface cracking?
Funny aside, I got a crazy high quote from a contractor to paint my previous home. I wanted a licensed contractor because I was going to be away on business while it was painted. I am also blessed/cursed with an eye for detail, so I needed to assure quality work, but at mustachian prices. The first guy was a referral from my realtor, after I saw his awesome work on her house. Alas, his quote was through the roof. I kept asking around. A neighbor mentioned a work colleague who was a contractor and painted houses on the side. Perfect. That was the man who became my husband eleven years later. Weird fact: we now live in a house that was built by the guy who gave me the crazy-high paint quote.