I have also been getting this message last few days, ie:" We could not complete your iTunes store request. The iTunes store is temporarily unavailable.Please try again later"
I have emailed apple support & one of their suggestions was to ask here! I know it is not a problem my end as it was fine until last week & others here have the same issue. Like another post here I do not want to upgrade from itunes 8 unless I have to. For info the reply from apple support follows:
Greetings from Apple iTunes Store Customer Support. I am Abdul and I am glad to assist you with your concern.
I understand that you are unable to connect to iTunes Store as you are receiving the error "the itunes store is temporarily unavailable. please try again later". I apologize for any inconvenience that may have caused you. Rest, be assured that I will do my best to get the issue resolved.
I have verified that the iTunes Store is functioning and accepting connections, which indicates that the issue is related to your internet connection, local network, or your local computer itself. This article outlines some of the likely culprits:
http://support.apple.com/kb/TS1368
Apple Discussions are another source of information about iTunes, where everyone from new users to professionals can interact and share their knowledge and experiences. You may find another user with the same operating system or ISP that may be able to help resolve this issue. You can find the iTunes discussions group at:
http://discussions.apple.com/category.jspa?categoryID=149
If the issue is still not resolved, please feel free to write back to me. I will be more than happy to help you with this.
Thank you for being a valued iTunes Store Customer. Have a good day!