Welcome Rudi! On doing a quick search, other than coming up with likely the same hits as you of those on ebay or worthpoint I did come across this bit on another site......
http://staugustine.com/stories/102305/off_3405156.shtml (this is dated Oct., 2005)
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Q. Please tell us about a desk that was recently given to us. It opens like a piano to expose the writing surface and cubby holes. The drawers are dovetailed. It's marked: "Hekman Furniture Co., Grand Rapids, Mich."
Because the old finish is in rough condition, my husband would like to refinish it, but I would like to know its value first. I know that antiques can be ruined by refinishing. -- M.E., Riverview
A. Your spinet desk was manufactured during the late 1920s or early 30s. They were popular during the Depression era because they were small, functional and inexpensive. Many factories produced them.
Designed after early spinet pianos, the desks were meant to compliment Early American interiors. Quality varies greatly and it's not unusual to find spindly versions with major problems.
Hekman Furniture was established in 1922. It expanded over the years and eventually was bought by Beatrice Foods. In 1983, it was purchased by Howard Miller and continued to grow. It's still in business.
These desks are very common so it's ok by me to refinish them. However, I would first consider repairing the old finish rather than go through the messy and time consuming process of removing the old finish.
In its current condition, your desk would retail for around $60. Even the best examples of these inexpensive desks sell for no more than $125. Hats off to you for caring about originality."
Other members here are more knowledgeable and up to date on current values according to market and location and I'm sure they'll chime in. Hope this helps a bit.