Gonna post some inexpensive backgrounds.
The backgrounds from GoFusion are
Journey to Valefor Academy.
Peyo's Reading Spot,
Underland Battlefield, and
Famestar Masquerade Ballroom all cost less than a billion. In GoFusion, they cost 20 hearts and 3 stars, so it might be cheaper to buy the charms.
The price on
Epic Journey is dropping a bit, you can get it for less than 2 billion. Has 4 fantasy backgrounds, and they're all quite different from each other so the item is very versatile, and thus worth the price.
Jaguar's Curse is 1 billion, not bad for some cool ancient ruins. It also has jaguar ears, tail, and eyes.
Not super cheap, but
Wicked Water Nixie is the most inexpensive of the Water Nixie items, running 1.5 billion. In addition to the pretty pond, you also get nice hair and flower accessories.
The RIG
Arctic Atmosphere has lots of lovely winter themed backgrounds, and they're all available at low prices. Just type
atmosphere in the MP search. With the exception of Zurg Abduction, they're all available for less than 1 billion.
If you like Astra backgrounds,
Smoldering Desolation is 2 billion.
Cruising Cumulus is one billion.
Celebration Fireworks is less than a billion.
Cool Lunar Phase is the cheapest of the Lunar Phase items, running you 2.5 billion.
Rolling Rainstorm is one billion.
Foggy Day is 2 billion.
Sparkling Night is a gorgeous night background with shooting stars, and it's 800 million!
At four billion,
Fantastical Journey isn't very cheap, but it has a good amount of variety so if you use background items, it's a very good deal.