How to Buy a Horse
You can’t buy a horse in game, but you can get it for free. Meet Mugi for the first time during spring (as early as possible recommended), and he will send you a pony the next day, asking you to take care of it. Now, make sure you talk to the pony everyday, and buy a brush from Saibara to brush it everyday. Mugi will attempt to take it away during end of year. If the affection of the pony is high, he will give it to you for free. Else, you will lose your only opportunity in getting a horse. Beware.