Please seek expert advice. Only take my advice for what it is...just some guy rambling on the internet.
Alright I have purchased many houses that have needed foundation repair. My own personal house needed it. The very first house I purchased needed it. So with that said it doesn't scare me one bit.
The first house I bought I had no idea about remodeling. I knew the house needed foundation work but I had no idea what that meant. So I got something like 7 bids. I finally settled on a company. Let me tell you I got bids ranging from 9 piers to 35 piers. What did this tell me? It told me that either everyone in that industry was morons or someone was trying to screw me. It turned out not only someone was trying to screw me every single person but the 9 pier bid was trying to screw me. I didn't know anything and I ended up accepting an 18 pier bid(The engineer later lowered this down to 12 piers...SEE WHAT I MEAN?). I thought maybe the 9 pier guy was wrong. I later found out he was the only honest guy. The second house I did I had a couple people come bid on it. The guy who did the first deal and the guy who bid 9 piers on the second house. I ended up using the guy who bid 9 piers on the second house and have used him ever since. It was from him that I learned that most guys bidding the job gets commissions based on how many piers the house needed. Do you think a guy who makes $100 commission per pier might add in a few extra piers? I would say hell yes.
From looking at the pictures you showed that looks very minor to me. I have gotten very good at estimating foundation repairs. Before I have my guy out I usually make my guess and I have been dead on to his estimates most times. Of course that is just me looking at that one picture. That is why I say get a good company to evaluate the situation.
Another thing you can do is get a state certified engineer to evaluate it. They will charge you like $300 but you know he doesn't have any secret agenda to profit from you. He will most likely speak the truth on what you need.