Check of a UK used car search shows the Bimmer is about $4000 over your limit
Boxster on the other hand could be bought for your price, but only if you buy the ones with the ugly headlights. These were never popular. Even in the 911 models and could be had for less than the clean line models
Nicer lens models are about $10,000. Ugly at your price. Bear in the mind these are the first series so will be the oldest cars.
Don't own either.
DON