Sec. 18. (a) Notwithstanding section 1 of this chapter, this section does not apply to a purchase of supplies by any of the following:
(1) A political subdivision.
(2) A state educational institution.
(b) This section does not apply when the purchase description is limited to soybean oil based ink.
(c) There is a price preference of ten percent (10%) for soybean oil based ink.