I know it was hit and miss but Princess seem to of removed the Best Price Guarantee for shore tours completely, the form has been taken down, the FAQ section gone and the bit at the bottom of the shore tours page removed.
Where it used to say: "If you find the same excursion for less elsewhere, we will offer you 110% of the price difference back to enjoy in the form of a non-refundable onboard credit"
It now says: "We offer competitive pricing, friendly service and unmatched destination expertise."
Put in a request before they changed it, not heard anything back yet after a week+, and was going to put in another when I noticed it's all gone.