how bad is this rust?

Well I put the car on craigslist and a mechanic came to look at it for his nephew. He inspected the car and said that was the only problem with the car was the one quarter of the frame. He thinks battery acid leaked on it because the rest of the car was just cosmetic he said. I couldn't find the rails on eBay but I do know a few people with home shops I could ask to teach me. The mechanic who looked at it even said the front suspension was new expect for the upper control arms. Does this effect your previous opinions at all?