I have an old camera!  

As You say, they can go for over $100-$150 in good condition, It's important for it to have a fast and Quality lens on it though to reach a good price, like an f2.8 or 3.5 Carl Zeiss Tessar.

I remember the Ikoflex...haven't seen one since the late 50s and I am surprised they still bring so high a price. As a TLR it was always a second best choice to a Rollei. Zeis Ikon have always made quality cameras with top glass, but if you can still get $100 for it I think you should take it, if you need the cash... but I reckon it is probably the sort of thing that is more valuable as a talking point on your mantle piece.