I went on Amazon.com this morning to check how well A Christmas Wedding Wager is doing. It is part of my routine to check on my books. Sad, yes, but it helps from going around the twist.
In any case, I have discovered that for some reason Amazon.com is temporarily out of A Christmas Wedding Wager. I did some fast checking. Barnes and Noble still is showing copies as is eharlequin. So I suspect that it is still relatively easy to get a copy and that it is just an Amazon supply problem. I mean after all the official publication date was only Saturday!
Of course, if you are willing to buy ACWW as an ebook (in any of its variations), there are always copies available. This includes Amazon Kindle.
The UK version of A Christmas Wedding Wager -- Christmas by Candlelight remains readily available from Amazon.co.uk.