The local places around me start at $89 and a few weeks for service (or did when I asked a few years ago). I don’t doubt that that’s a fair cost for someone’s labor, but it is a little hard to swallow when it approaches the cost of the machine itself. I paid $50 for my old Janome L108 on Craiglist, so when it stopped working a few years ago I hit Google first. Knowing nothing about the brand you mentioned, I’ll note a few things: some machines have all powered components in series, so if your bulb blows (this was my problem), your machine won’t work. Most foot pedals have a potentiometer in their wiring to allow for the variable speed, and they can go bad. Cleaning and oiling your machine yourself is REALLY straightforward – your owner’s manual ought to show you where to dust and oil. That might be all your machine needs.
You can also often find the servicing manual (not the owner’s manual) online for a few bucks – it’ll have internal diagrams and often part numbers. If you or she enjoys that sort of thing, and you’re OK with replacing the machine anyway, you might as well take a crack at repairing it.
For what it’s worth, although I haven’t found it worthwhile to get my machine regularly serviced (I can clean/oil/replace belts), I absolutely would pay to get it *repaired* if I couldn’t fix it myself, even if the cost would all but have to exceed the price of my Craigslist special. It’s solid metal, it runs like a champ, and it does everything I need it to. And I *like* tinkering with it – if I had a pricey computerized machine I’d be a lot more leery of taking a screwdriver to it.