I lease and well I went a little crazy when I went tack shopping. Some of the tack that I got replaced old tack that I no longer use. I got a saddle, a bunch of saddle pads, first aid kit, buckets, bath supplies, first aid sprays etc. a bridle, a tack trunk, halters, lead ropes, fly gear, tack cleaning supplies, grooming kit, and any other little odds and ends a horse may need. The only thing I did not buy were a girth which I want to get because I am not a fan of the one he has and I want to get a bit because I want to have 2 complete bridles. So basically I bought everything except blankets as if I owned him.
Your horse is an extension of you.