I use only top quality Leather halters, so they need replacing only every 4-6 years. I clean and condition them about 3-4 times a year, bathe my horses in them, and store them in my tack room when not in use. My last halters were Horsefare Leather Halters
and they did really well. They still are functional, just "worn". I ended up giving them to a friend and she's using them as turn-out halters for two of her hard to catch horses. They've been on them for 8 months now and they're still going strong!
My current halters are ThinLine Padded Leather halters
. I like the leather and hardwear, but after 2 years of use, the ThinLine padding is starting to get some minor surface cracking in it. I probably won't be buying those again (especially considering the $125 price tag!).
I buy new fun colored lead ropes every year though