I would first start off by saying that what one would consider to be a 'problem', another might consider to be an 'annoyance'. So, it's subjective as to what one would describe a mouse problem to be. I guess it comes down to a 'tolerance level' or somethin'. That's just as an aside ...
Just 2 days ago, after moving around a few boxes in the basement, lo and behold, I found a dead mouse. It's the 2nd one in about a month. Now, I wouldn't call this to be a problem but my wife does. So, I've set a trap or two. (We'll see.) Anyways, if you have the work done as you describe, I think it would be safe to say that you've certainly reduced your 'exposure' to a mouse problem. At the same time, to keep tabs on this, I'd set a few traps around, especially in winter (which is most likely when they come in from the cold), to see if you catch anything. If you do, you'll know where the problem is. If you don't catch any, well, only at that time you can safely say don't have a problem.
You have to try and think like a mouse too. Think of where they can enter the house and where they might go once they're in. Think of what they might use for their nests. And what they may get into for food. That's where you put the traps.
I have to add a caveat - W/O knowing how 'pervasive' your 'problem' is, I can't say if you should buy the house or not. My best to ya and hope this helps.