It is not an easy question to answer. A Fishtales might be valued at $2600 and be that price at several dealers. But the level of workmanship to arrive at that price can be a huge difference. It has been a buyer's market for almost 3 years, and there are more machines arriving in Australia at this point in time. So you need to do your homework so that you obtain full value of your purchase dollar. There are more short cuts out there at the moment, and the standard of reconditioned or "shopped" pins is at it's lowest for many years.

My tips would be ;

Decide on a shortlist of pins
Decide on a price that fits your budget
Look around and personally view dealer's games. If they are dealer's pins on eBay, look at them "in person"
Ask HEAPS of questions here

Try to visit collectors and ask them about their experiences in buying pins and also play their games.

The most important tip - DO NOT buy a pinball "on impulse". This always ends in a disaster.