US$125.00 is (was) a good price for this scanner. Here in Australia they cost much more new, and still bring in a good resale price on Ebay.
Christopher Coy, hang on to your 4990. It is now regarded as ancient and worth almost nothing (to be kind) on the sale market.
In its time and properly used it produced wonderful scans. I bought one many years ago when they were being sold in the USA but not yet in Australia. Carried it back with me as cabin luggage on my across-the-Pacific flight (the good old days of international flying). I set it up at home and undertook a long learning curve (early internet years) to figure out how to properly use it. My scans did need a LOT of post processing work but the results were astoundingly (or so I thought, and still do) good for the effort. At the time I was still an architect (now retired) and I made many scans for clients who were entirely satisfied with the results. Some were published and look as good today as anything professionally made today.
I now have a V600 and a Plustek for my 35mm. The V600 scans MF negatives well, slides okay, B&W superbly. The 4990 has sat in its bag for some time but I do take it out a few times a year to put it through its paces. Software is now totally obsolete but it still works. I believe Viewscan will work on it. The results from the same negative scanned on either of the two scanners really cannot be identified one from the other when viewed together.
In today's technomad world it is all too easy to forget that many old things continue to function and produce results as good as anything made now. So much of our 'new is good' thinking and attitude is basically a marketing ploy foisted off on us by photo gear manufacturers who want their corporate profits padded by our hard-earned dollars. Two good examples are the Rolleiflex TLR and the 4990 scanner. This is not to say the new V series scanners are not good, rather that the older scanners if used carefully can go on producing results entirely acceptable to us and to professional printers and publishers.