Never seen that game in person. It's always a good idea to go read Marvin's site on the type of pinball you're interested in so you can see what's all involved with repairing one.
The biggest concern is to make sure there isn't battery corrosion on the CPU. If there is, you can either buy a repro CPU or PASS ON BUYING THE GAME. A little corrosion can be cleaned up, but major corrosion isn't worth the trouble.
Considering only 900 were made, you'd better make sure the backglass and playfield plastics are in good shape, as you'll probably have a hard time ever finding a replacement.
Usually, I tell newbs to shy away from the 77-85 solid states if there are any problems, but if it's working great and looks great, then there is no reason not to get one. Pinball's tend to hold their value these days, so you should be able to get your money back later if you wish.
I'd say - play it first. If it's fun, buy it. If you go "Eh!" and just want a pinball, wait for something better...