Bundle of Holding - Lamentations of the Flame Princess
Say what you want about the Lamentations of the Flame Princess releases (and much has been said) but the quality of the art of the strength of the writing is top of the line. Usability? That's a whole other question and depends on the title.
Carcosa and Isle & Dungeon of the Unknown are very strong, if off kilter, sandboxes. Death Frost Doom 2e has always reminded me of a survivable (strange to say that about LotFP) Tomb of Horrors. Blood in the Chocolate is disturbing as all hell. The Monolith from Beyond Space and Time is a useless party fuck IMHO and Lamentations of the Flame Princess - The core ruleset. You get the above for $14.95
As for the Appalling Bonus Collection, this is a much stronger collection. I have nothing but good stuff to say about the choices and if nothing else your reading will be enjoyable. How much will be usable in your campaign will depend on you but lots of ideas to borrow and steal. My two favorites picks from this batch are worth the price of admission on their own - Broodmother Skyfortress and TowersTwo. These are simply amazing examples of great adventures to inspire the DM. Currently priced just short of $27 for the bonus collection.
The Minotaur for Old-School Essentials
*Requirements:* Minimum STR 9, Minimum CON 9
*Prime Requisite:* STR and CON
*Hit Dice:* 1d10
*Maximum Level:* 8
*Armor:* Leather, including shield...