Price listed in Refurb Store different than what I was charged

Not sure if this is the right sub-forum for this question but can't seem to find any other that fits.

I ordered a refurbished Mac Mini from Apple. It shipped out yesterday, allowing me to print the invoice. I noticed the price on the invoice is about $45 less than the price listed when I ordered it. Not complaining, but any idea why or how this happened?

No, I did not order anything else with it.

Sales tax would not explain it. The listed price for the Refurb 2011 base model Mac Mini was $515. When I received the invoice, it was $469. I noticed the 2010 models were listed at $469 about this time last year, so maybe I caught them just as they were dropping the prices for the 2011 refurbs. I did verify that the model # is the same on the original order and the invoice. Can't help but wonder if this means we are going to start seeing the 2012 refurbs for $515 (base model of course).

In the end, I am even happier now with my decision to purchase the refurb base model.