We are looking at buying a house that has a wet weather spring under it. The house sits on a slope, the spring has popped up on the upper side of it about a foot or two from the foundation. The house is only 5 years old and they only noticed the water under the house last year. They have dug a pit right at the spring and installed a sump pump and are piping it outside. This spring does not run constantly. There is no damage from moisture under the house at all. They have put a layer of rock under the house with a layer of plastic over it as a moisture barrier. My question is do you think this house is still worth considering or would you run?

An under ground spring is not desirable but is not all that unusual. Whether to consider purchasing it depend on how much you like the house. If I were going to buy it, I would plan on piping from the sump crock around the house to the lower side if at all possible. The sump pump is fine except that the electricity is most likely go off during the worst weather. The drain line will work all the time. It can go under ground to a lower spot and then come up out of the ground with a pop up cover. The place where it comes out of the ground only has to be lower than where the pipe connects to the sump crock. Biggest expense would be the digging.
The plastic under the house is good but I wonder what the present owners thought the rock would do for them.

Harold's suggesting a french drain, (see image) and I fully agree with him. A natural drain's much better the one that depends on power to run it.
Good luck, Tom