Around 1987 I got this at a police auction for $12.50. Scrounged up needed parts, bought a new rear sight and made a front blade. Refinished the wood and blued it at home for another $9.50. Total monetary investment is $22.
Cheapest rifle that required no work is this Turkish Mauser I got off Gunbroker about 5 years ago for $81 (including the bayonet).