Kansas highway 25 from the Nebraska state line to interstate highway 70 is hereby designated the Great Plains Indian highway. The secretary of transportation shall place highway signs along the highway right-of-way at proper intervals to indicate that the highway is the Great Plains Indian highway, except that such signs shall not be placed until the secretary has received sufficient moneys from gifts and donations to reimburse the secretary for the cost of placing such signs and an additional 50% of the initial cost to defray future maintenance or replacement costs of such signs. The secretary of transportation may accept and administer gifts and donations to aid in obtaining and installing suitable signs.