That sounds like the normal price on sale right now. Are you sure you are logged into "My Account" and clicking on your license? Did your upgrade protection expire/lapse? It should tell you if it expired, or is expiring on a certain date.
But the Enterprise with 250 mailboxes should be the same price. There shouldn't be a regular price in there at all when you go to renew your license, so it sounds like you went into Buy Now instead of My Account, and choose your license.