https://www.ebay.co.uk/itm/1-72-Boeing-X-20-Dyna-Soar-3D-Printed-Model-Nasa/124295875137?hash=item1cf09c8a41:g:6dsAAOSwHURfM~rM
Looks to be rather good and done with resin rather than plastic. Price is perhaps a bit steep but the same seller does a load of the Space X stuff too.
Thats a fairly reasonable price for an SLA 3d print of that size. It looks rather good in the pics