The electrical wiring was a nightmare, but luckily didn't cost me much to repair. Fortunately I'm an Electrician by trade. But it still took a good few days to get everything up to standard. And the previous owner was quite the gentleman and reimbursed me for the costs. He was also honest enough to tell me about the problem before I purchased the house.
Which is why it didn't bother me much. It was not that big of a problem to me. If I had to get an independent contractor. Well, then it would've been exponentially more costly.
What did you have to fix after purchasing your first house? And did you know about the problem before buying the house?