Reddit mentions of Catan Scenario: Oil Springs

I would go for the Catan scenarios. We have had a ton of fun with the Oil Springs scenario. They are really cheap too. They can be hard to find because they are really small, but at your local game store look for a package that looks like a piece of cardboard wrapped in plastic. I think it was something like $5-$10, so probably the best expansion for your money. For Oil Springs they only charge enough to cover production costs and any extra profit goes towards Worldwatch's Transforming Cultures Project.

Oil Springs introduces a new resource (oil) and new settlement level (metropolis, 3 of everything), and a whole new game mechanic. As you use oil global warming occurs and you can lose tiles and coastal settlements and downgrade cities. Playing with my friend once he had three cities around an 8. Then I used oil and triggered a global warming event that took the 8 off the board. Then on my next turn I caused sea level rise and two of his cities were destroyed. If you upgrade your cities to metropolis they are immune to sea level rise. If enough global warming events happen the game is over and the player which sequestered the most oil wins the game.

Here are the rules for the Oil Springs scenario if you are interested: http://www.catan.com/en/download/?Catan-OilSprings-Scenario.pdf

And the link to the game on amazon, it even has prime: https://www.amazon.com/Mayfair-Games-Catan-Scenarios-Springs/dp/B006GHRSLK/ref=sr_1_1?ie=UTF8&qid=1502733630&sr=8-1&keywords=catan+scenarios

Edit: you can also download it for free

Edit2: Video review of the Oil Springs. I watched a few reviews to find the best one, this one has a couple slip ups, but overall its the best.
https://www.youtube.com/watch?v=4xiz3jnm5dA