All printing, binding, and stationery work done for any state agency, county, city, town, port district, or school district in this state shall be done within the state, and all proposals, requests, or invitations to submit bids, prices, or contracts thereon, and all contracts for such work, shall so stipulate: PROVIDED, That whenever it is established that any such work cannot be executed within the state, or that the lowest charge for which it can be procured within the state, exceeds the charge usually and customarily made to private individuals and corporations for work of similar character and quality, or that all bids for the work or any part thereof are excessive and not reasonably competitive, the officers of any such public corporation may have the work done outside the state.