Basic (Mentzer) D&D - While perhaps not the best iteration of Basic D&D, it's also perhaps the easiest to learn. 96 pages, $4.99
Companion D&D - This is actually the only D&D (as opposed to AD&D) book I owned back in the day. Rules for levels 15-26, but more importantly/interstingly, rules for running a domain (which AD&D lacked). 96 pages, $4.99
Bows 1 - ( magic bows. 50 cents, 4 pages
Swords I - 9 magic swords. 99 cents, 4 pages.