If the camera really is in good working condition (many FXes have broken lightmeters, sticky shutters and disintegrated light-blocking foam: these things can be fixed, but for several times more than that price), then $25-35 is a good price indeed (I bought my FX, in about 1996, for £50 (GBP) with 50mm f/1.8 lens and a broken light-meter).
In relation to the light meter, if it's still working (it's not TTL: the camera dates from 1964, so you can't really expect miracles ;-)), it takes mercury batteries - the sort that they don't make any more for environmental reasons. One can, I think, buy specially made alternatives, but they are costly and otherwise problematic.
The FX is best used, as I use it, with a separate hand-held light-meter (which is the best way to get an accurate exposure in any case), so even if the light-meter is broken, this isn't a serious problem.
If you are after resale, however, then, whilst I can't give you exact numbers, I've seen FXes selling at second-hand sites on the internet for three figures in US$. Whilst I'm in the UK, and can't calibrate very accurately for your currency, even £35 would be good for an FX that really is in full working order, so, if the seller is reliable, go for it.
If you really don't want the camera, send it to me: I'll look after it ;-)