I am one of the lucky few who gets to fund my addiction with my addiction LOL. I cut costs by looking at tack and things that don't have to be name brand.
I use the $8 halters instead of the $30 ones. I buy the reins that are still good harness leather but they are an off brand and only cost $35 instead of $50+. They both work the same, one is just an off brand and therefore cheaper.
I buy all my clothing when it's on sale and sometimes I buy off or store brand clothing.
I make cuts where I can and avoid buying things that I really don't need like a new bridle just because my other has a couple of scrapes that make it ugly.
I make sure to clean my saddle pads and girths often so that they last longer and don't degrade from sweat and dirt.
I make sure my horses have good feed but I don't buy any extra supplements or add-ins unless it is an absolute necessity.
I don't go out to eat very often, it is much cheaper to cook for myself at home.
Etc, etc, etc.