One of the more horrific color choices I've seen in a while.
I like that it's colorful, even if the colors are kind of hamhanded; it's good for your office to have an identity. I wish we could paint our offices (we could, but we need to be able to trade up to bigger offices on very little notice).
Assuming you can find a cheap printing place, there are tons of high resolution creative commons images on flickr and elsewhere.
My university has a super cheap copymat, it may be that a university near you has similarly cheap prices.