I came up with generic horse price for my campaign, and then modified them if necessary.
size base price base move rate horse, light riding 25 gp 26” horse, light war 75 gp 24” horse, medium war 110 gp 18” horse, heavy war 130 gp 15” pony 20 gp 12” quality price difference movement add poor -50% +(2d4-6)” ( -4 to +2 ) average —- +(2d4-5)” ( -3 to 3 ) good +100% +(2d4-4)” ( -2 to 4 ) excellent +200% +(2d4-3)” ( -1 to 5 ) superb +265% +(2d4-2)” ( 0 to 6 )