Pinball machines are a bargain pro-rata for what they give you. Its not that dear to maintain or do them up. AND they go up in value over a reasonable time.
Name something else that visitors/people coming into your home get that excited about. !
I had a couple of 1978 2 door XC COBRA Coupes. They went up in value every year, but everyone wanted to steal them, and if u parked at a bar or a restaraunt, with the car outside, you couldnt relax for 5 minutes.
The cars were fun, but everyone else can enjoy the Pinballs and u also get to meet lots of top blokes/other collectors. Pinball can be a affordable hobby for everyone.