l am thinking about getting a Porsche Boxster for my wife, is a high mileage Boxster good as a daily driver? How reliable are they? Anyone have one with over a 100,000 miles? If so how long have you had it and how good/bad are the repairs?

If it needs to be repaired, it will be very expensive. Anything over 100,000 is going to need periodic repairs to keep it running. If you were going to get this and drive it on weekends and nice days, it would make more sense, but as a daily driver you may find the repairs cost you as much as a new car.

this is potential for it to be expensive. parts will wear out and need replacement like any other car, and it is hard to service the car yourself unless you have access to a vehicle lift (it is hard to get to the engine in a mid engined car)

you might be better off leasing a new one, or getting a slightly newer car with a warranty

Yes, they are very reliable. Probably the most reliable German made cars.

l drove a 1998 Porsche Boxster with 60,000 miles. It was great.

My neighbor has a 2006 Porsche Boxster S and he uses it as a daily driver. He never had problems and he says it is a great car.

l would get a sports car where they have more development time and resources to put into the engine like a Ferrari 308 GTSi, you can get like 1981-82 for $30,000.
There are plenty of manuals on how to maintain it yourself.

Road & Track did a used car classic feature on the Boxster. The list of problem areas was pretty overwhelming. One of them was the engine, to the point that Porsche mechanics call the CEL(check engine light) the Change Engine Light instead. Unlike many German cars from the 1990's, the Boxster is not even a good hobby car for a shade tree mechanic, unless you have a lift under your tree and time to drop the engine and rear subframe when you're ready to tinker.