If you're not planning to finish the basement as habitable space, the measures you're contemplating may be enough. But if you plan on finishing it, yes, waterproof from the outside with new weepers, asphalt cutback and a plastic membrane.

The biggest cost is excavating, especially if it's surrounded by driveways, patios or other buildings. All costs are local, so contact a local waterproofing company rather than fishing around here.

My advice: Be sure to talk to a water remediation company or two for estimates before you sign off on the house. The work may be much more costly than you expect, especially if the result your are hoping for is a completely dry basement. We have had to excavate the perimeter of our house and to do that we demolished the decks and porch and now we are in the process of replacing those. Very costly.

J Inhof, we have no decks or porches, and are intending to do a lot of landscaping around the house anyway. Are you happy with the results from your waterproofing?

Unless there is an obvious reason why the house would have a serious water problem -- like sitting in a depression at the base of a big hill or having a creek in the back yard ;^) -- I'd do the needed repairs (fix gutters, downspouts, etc) to get the water away from the house, run a dehumidifier to get the basement properly dry, and then wait and see what you're dealing with. I suspect the moisture issues will be resolved by those fixes, especially since the home inspector apparently didn't flag it as a problem.