If you haven't already preordered Heavensward, Green Man Gaming has a coupon code available for 25% off the PC version . It's good for both the standard version and the digital collector's edition. The code is:
25OFFF-FHEAVE-NSWARD
You have to create an account and sign up for thier newsletter to use the code, and it's only good until June 5th. GMG is always doing some pretty solid deals on both new and old games, so it's not a bad idea to be getting thier newsletter anyway.