What to do with valuable chairs that are beyond what I can afford to refurbish  

First of all, welcome to the Forum.  For any question, photos of the item are always helpful, but I will assume you are asking about the chairs shown in the photo here.  To start, Stendig was not a manufacturer, but an American importer/dealer of furniture from a number of European countries.  These chairs, model RH-304, and sometimes called Unesco chairs, were made by the Swiss maker de Sede.  They continue to make them today after re-issuing in 2010, and from what I can tell, new versions retail for around $2200 each. 

As far as vintage values go, do not look at asking prices on sites like 1stDibs and Chairish, which are wildly inflated.  Look rather for sold prices on sites like Liveauctioneers, as shown here.  This pair was sold by a Zurich auction house for 650 Swiss francs (800 with buyer's premium added), so about $800 US since exchange rate was around 1:1 at the time.  And a set of 10 sold for $1,300 at a Florida auction house in 2019.    Based on these sales,  and values for similar chairs, I would estimate value around $300-$400 per chair in good condition.   

That brings us to the depressing subject of reupholstery cost.  I've never had leather furniture reupholstered but my guess for chairs like this, with new foam and tufting, would be around $500 per chair in most US metro areas, maybe more.  So, if your goal is to have a nice set of chairs to use and enjoy for the next 30 years, reupholstering might make sense.  But if you want to sell the chairs, you'll be fortunate to recoup costs.  It's a sad situation I've found myself in a number of times.  You could try re-dyeing the leather, maybe a slightly darker color.  I've used Fiebings dyes on leather chairs with good results.       

I would list them on the free sites like Facebook and Craigslist if you are in a major metro area, and maybe Ebay too, though shipping will be another big cost for six chairs.  You can start with whatever price you think is fair, but be prepared to discount them every couple of weeks until sold. Good luck    

Mark 737.  Thank you very much for your response.  Very thorough and I appreciate the education about what they are.  I will have to discuss with my siblings.  Very helpful.

thanks,

Melissa