Best Value for Money RPG Purchase

[Philotomy Jurament]

Hard to choose one, but the best books I've gotten the most use out of:
...
Call of Cthulhu BRP

Oh, there's a good one, too. I bought the first edition CoC rules and used that rule set for years and years. I finally upgraded to 5th edition when I was out-of-town and somebody wanted me to run a Call of Cthulhu game -- that's the edition they had at the FLGS. Really, though, I could still be running Call of Cthulhu with the 1st edition rules and with current edition (6th) supplements; the game hasn't changed much over the editions.

 

[Herzog]

Wrath Of The Immortals Boxed Set (OD&D)

I have used it to run a campaign over a period of 5 years.
It has been on hiatus for over 2 years now, but the players still bug me now and then to pick it up again.

 

[Aus_Snow]

I omitted a *major* bargain from my previous post, and this one's actually D&D related!

The Broken Isles (a setting and rules bundle in PDF format, by The Inner Circle), which I preordered for a grand total of $0.99.

I was expecting to buy it at full price (and was totally fine with that prospect), but preordering took it from just a very cool 'must-buy' to a very cool 'must-buy' that has to be one of the best all-time uses for that kind of trivial sum.

 

[Hussar]

For running an urban campaign, I would point to MEG's Urban Blight series. This book never stayed closed when I ran a SL campaign set in Shelzar. Of the 20 locations, I could use seven right out of the book and another seven with minor alterations. A book that I can use 2/3rd's of? Gimme more of that.

 

[Job]

This is an easy one for me!

1. Shackled City Adventure Path (this campaign has provided endless hours of fun for my players)
2. DM Genie (This product is amazingly good at helping me run my game!)
3. NPC Designer (Instant stats for all of those campaign "walk ons". And it works VERY well with DM Genie).

Job.

 

[Li Shenron]

Someone among Rokugan Campaign Setting, Manual of the Planes and Unearthed Arcana.

 

[morbiczer]

Dragon and Dungeon subscriptions.

 

[EricNoah]

Recent purchases that have seen a lot of use:

Lords of Madness
Libris Mortis
Complete Psionics Handbook
eTools (not a particularly recent purchase I guess)
FR Interactive Atlas (definitely not a recent purchase)

 

[JustaPlayer]

Conan RPG by mongoose at $20.

I'm not sure yet but it may change to Ptolus at $45.50

 

[bento]

Kara-Tur Campaign Box Set from RPGNow for $5.

My USB thumb drive to hold all my notes and pdfs - $20