The current Bundle of Holding is up, and it has:
Labyrinth Lord Revised Edition (retail price $6) AND the Advanced Edition Companion (retail $7): The full illustrated retail versions of Daniel Proctor's Labyrinth Lord rulebook (a leading B/X D&D retro-clone) and his Advanced Edition Companion (a compatible AD&D first-edition clone).
Dyson's Delves (retail $10): Over 140 pages of beautiful subterranean maps by Dyson Logos, including five adventures for levels 1-8.
People of the Pit (retail $7): Brave Halfling's compelling and dangerous adventure for levels 5-7, based on a classic 1918 short story by A. Merritt.
I can vouch for the interest and value of the first two (here is a review of Labyrinth Lord. Dyson's work is never to be missed, either.
$7.95 for the lot is a good deal if you don't have any of the four.