Kathleen. You are trying to solve a very tough problem. Water (guess what, it is a fluid) and likes to do all sort of wierd things. Like, travel underground and come up right under your pool table. Or, if there is not enough "charge" in the surrounding contributary area, wait until you think there is not a problem, then come for a visit. It depends on your soil type and where you are in relation to run off. If you live up high, consider yourself lucky, if you live in a low area, and water loves low areas, you have other problems. If you live in town with streets and gutters and storm drainage, that is a consideration in determining problems. If you live in the country and have a beautiful view of nothing but the Rock Mountains, then you have a different issue. If the soil is sandy, good, if rocky, can be bad.
Point is, this is not simple. Having the gentleman "inspect" your house is a definite options. Hopefully, being local, he knows the issues of your area. But, if you live in a very sparce and rural area, these guys don't exist. Another problem.
The contractor you spoke with may actually have had the solution. You did not say "why" he wanted to do what he said he had to do. Perhaps he is right.............but the price is a problem. Perhaps water is why the house was for sale. You have some options there is there was any cover up of this problem, ya' know.
I do not envy your problem. Water is no fun and I do not mean to be discouraging. Hopefully it "is" a simple issue of proper guttering and "surface" water. You are being smart.........consider the advise you have received on this message board, arm yourself with more information........then "repost" an you will get as much help as we can give you. $8000 is no fun.