If things change I will drop you a message.
The challenge with STTNG is the complexity and age with it, which to be honest I very much underestimated. (Before I owned one I had never seen underneath a machine!) You will be fine if you purchase a clean, well maintained/restored/parts updated one. Although they will go wrong from time to time, as most pinball machines do. Expect to pay on here £3.2 to £3.5K for a good one. (possibily a little more) Altough I'm sure there will be people on here saying you can get one for £2k
and you might, but expect to pay at least £1k fixing it!
A couple of tips if you still want one:
1) Make sure there is no battery damage on the board
2) Make sure the ball hopper assembly has the correct coils, most of them in the machine are AE-23-800. (they are printed on them)
3) Make sure the 3 flippers have the right flipper coils, FL-11629 (blue). From personal experience the wrong williams ones will work, however they will damage the fliptronics board over time.
4) Make sure the subway, the large plastic thing is clear and you can see through it, means its been taken apart and cleaned. I thought it was black!
5) Make sure the divertors have the right coils- AE-25-1000. These are attached to the subway.
6) Make sure the coils /selnoids are clean, means they where changed recently and not in 1998! See my pics of old ones I took of the machine
7) When testing the machine make sure all the flippers hold, this is holding the button down, the flipper will stay upright, if it jitters or misbahaves in any way its most likely a problem with the fliptronics board.
8) Look at the opto's if the white ones are yellow its likely they have never been changed. The white fades over time, they might cause issues. There are alot in the machine
9) Make sure all the lights work and are not intermitant, missing some lights for me general illumination means most likely a problem with the powerdriver board.
10) play a 10 ball game with the factory settings on Extra easy, multiball set to 50%, this will play through all modes and you will get to Final frontier (unless your really rubbish) it will quickly tell you if there are problems. Ball's won't come out of the hopper (holes in the table, flippers will start to misbehave, mission's won't be possible, it might even look for balls from time to time
) If all good then your less likely to have any problems and it likely to have been well/regularly maintained.
My personal opinion is there no such thing as a bargin STTNG
(if you don't have the considerble time and expertise/blind luck/help to restore it) but being a newbie I might be wrong
If you do decide to get one, people on here are incredibly helpful and will normally point you in a direction to solve. I wouldn't have been able to fix mine without the kind help from people on here.
It is a fun machine, lots of modes and multiballs, however whats one man's pinball heaven is another hell
Thinking about it I might make my next machine a Stern playboy 2002......