i'll +1 that.
Some other things to think about:
- are you wanting to build an old, 26in wheeled MTB? - you'll be hard pressed to find a decent new fork, and even harder to find an old one
https://goo.gl/photos/om6FUVuHkAqnqpR18

- you have to think about steerer tube diameter
- tapered headtube or not
- wheel size (29in? 27.5in? 26in?)
- disk or not (almost impossible to find decent rim brake bikes now a days, i think...)

Anyway, I guess it depends if you enjoy the building things up from not much or if you enjoy riding more. And if you build it up yourself, you'll face the pressure of riding an odd ball bike in front of all the kool kids who bought the off the shelf kool bike from the bike shop.
Then you'll get a reputation for riding odd ball bikes. It happened to a "friend of mine" ~ not that my Franken-bikes are odd - they're kool.

Mountain bike suspension forks ? a buyer's guide - BikeRadar USA