These days, US copies of Nerf Arena-Blast are often considered collectible and can demand a high price, especially for complete in box copies. When my disc cracked, I decided to do some research to replace it. Personally, I bought my copy from this e-bay seller. The seller has a limited quantity however, so when they're gone you'll have to find another source.
While it is only the disc and no box is included, it is the UK version of the CD, meaning it is arguably the most stable and up-to-date version of Nerf Arena-Blast on a CD.