Don't bother with a tune up! Generally speaking machines that age can be maintained at home. I paid that much and it turns out all I needed to do was figure out where the oil needed to go (we are talking about a machine that needed oil dropped into about six spots on the outside!) and that the bobbin and upper thread tension needed tweaking.
I would though usually recommend something with a stretch stitch. Triple lock. This is the biggest revolution in home machines. Zig zag is really easy, it goes back to even chainstitch days, but the triple stitch basically does two steps forward one step back and that creates a seam that genuinely stretches vertically. So that means gears under the feed dogs pushing the fabric forwards and backwards under the foot (zig zag is the needle moving sideways.)
And whatever anyone says about zigzag being all you need, heck no. It is generally recommended for plain knits, and to hem them. It was never meant for spandex!
Anyway, once you have the triple stitch you also get decent decorative stitches that also stretch and they can be great for finishing hems in a way that doesn't scream home made
But yeah, I have a Janome, and it's the same one I mentioned here:
http://www.therpf.com/showthread.php?t=33403&p=435876&viewfull=1#post435876 and yes, I have maintained and restored it

Got the reverse to work again too.
Janome/New Home SW-2018E
http://zigzaggers.typepad.com/zigzaggers/2008/04/janomenew-home.html
(Same issue I had with reverse so I think it's an issue of the few plastic parts wearing out, but as said I managed to fix mine

)
So basically think of a muscle car and how you need a bit of mechanical knowhow and the model specifics and you can make them last for decades. Newer machines are more like newer cars and generally not built to last and are a lot more complicated.