Short answer: Lev Yashin is the highest-rated all-time keeper at $3 — only goalkeeper to win the Ballon d'Or.
Among 30+ goalkeepers indexed, top names by price/era: Lev Yashin (Soviet Union), Buffon (Italy, 2006 WC), Neuer (Germany, 2014 WC, sweeper-keeper template), Casillas (Spain). All $3. The cheapest current Premier League keepers are Pickford and Pope at $1.