There are alternatives. You could get Photoshop CC with updates forever with Creative Cloud for teams. That would cost $50/month for all 30+ apps per user, or $20/month just for Photoshop per user.
http://www.adobe.com/nz/creativecloud/buy/business.html
The final option, but one I am not sure is strictly valid for business use, is for each user to have a separate subscription for the Photoshop & Lightroom Photography plan, and $10/month for each subscription
Creative Cloud pricing and membership plans | Adobe Creative Cloud
I just tried to hunt down Terms & Conditions regards using the $10/month plan for business, but couldn't find anything.