Zip disks should work for about 30 years, and quality CD-Rs have a life expectancy of 75 to 100 years. CD-Rs in my opinion are your best shot right now. Manufacturers use environmental testing chambers to simulate the aging process and gauge the effects of temperature, humidity and other factors. I wouldn't buy from weird companies. Even if the information on your removable media remains intact, it will be useless if hardware to read that disk isn't available down the road.
Companies can stop making particular models of drives, or can go out of business outright.
For example, in 1998, Syquest, once the leading manufacturer of magnetic removable-media drives, filed for bankruptcy, creating headaches for users who needed repairs or additional media. Another insurance policy is to make multiple backups on different kinds of disks. Saving those honeymoon pictures on both CD-ROM and Zip offers twice the chance that the data will stay readable. And in the long run, it doesn't matter. How the media is stored will affect its life expectancy.