I would not sell it. Money can always be earned but one of a kind pieces of equipment may never be able to be replaced. A sky high price would be maybe $10,000. It could also bring not even a third or half of that.
A few extra hours at work or save a little by not going out or something and you will have the money equal to the combine in a short while.
I have kicked myself for years for selling an AC WD 45, diesel, wide front end tractor thirty years ago. I bought it at the original owners sale. I gave $1500 for is and sold it two months later for $2000. I thought at the time I was in tall cotton. I had made $500. I was making that each week at work so it was not a super big profit. I have watched for one even half as good as that one and the junk ones bring double what I sold that good one for.
It is yours to do with what you want. If you do keep collecting you will kick yourself for years to come if you sell it.