Colo. Rev. Stat. § 30-11-110
It is unlawful for any board of county commissioners of any county to accept any bid or make a purchase of any books, stationery, records, printing, lithographing, or other supplies for any officer of its county, from any person, company, or corporation having its manufactory or principal place of business outside the state of Colorado, when the same can be procured from some person, company, or corporation having its manufactory or principal place of business within this state and at a net cost which shall not exceed the amount for which such books, stationery, records, printing, lithographing, or other supplies can be procured and delivered to them by any person, company, or corporation having its manufactory or principal place of business without the state.
C.R.S. § 30-11-110