Installing new pins is a rare, special event - and one of my personal favorites.
New pins cost a ton of money, and are designed to last at least 12 years. A pin costs around $35, and 25 pins go into a machine. That's almost $900 per machine!
Installing new pins into improperly maintained machines will result in them looking old very quickly - so I never recommended buying new pins until the machines will handle them properly - and of course, our job is to maintain them properly. :)