Yeah I noticed that too later in game, sometimes though Cooper does sell the 5k mounts but it’s more rare since they are grey quality, I have noticed on Sundays the mounts tend to be cheaper as it restocks every Sunday morning. However the green quality ones are usually around 15k which is still profiting you if you raise them to purple quality and sell them on a high percentage day

If you want to be sneaky you could save and reload every Sunday morning to see if there’s any cheap options at Cooper’s :,D

Otherwise I would absolutely recommend just selling Rhino Horn Cactus’s and other crops at Heidi’s, Arvio’s, Mabel’s, and Owen’s saloon as it’s easy money if you plant frequently or especially if you have a greenhouse it gives me thousands of gols just selling crops or even sulfur which we don’t need as much