For you a 50w ballast might by hard to find but 50W HPS fixtures are by the thousands here. I'd just need to get a fixture lol. Shipping for the clear 50W lamp is $6.50 for me. Shipping for the Feb. 1985 coated lamps is $8.99 and shipping for the other clear lamp is $4.99.
BTW, if anyone buys the case of six coated 50W HPS lamps i'll gladly pay the $10 plus the money to ship the lamp to me if you're willing! I don't need all six though, just one.