An old post, but still valid ... or valid once again.
Tilt-A-Whirl is again/still available for $0.99 from
Amazon and
Barnes & Noble.
This time around you can also get the second book in the series, Mad Mouse, and the third book, Whack A Mole, for $0.99 each from both vendors. The easiest route is probably to find them under the product description on the same page.
I recommend these books without hesitation. I'm also looking forward to the May release of Fun House, the seventh in the series. I don't know if the special pricing is due to the upcoming release or if it will be around for a while longer.
(I used the "Search" function to see if these were mentioned in any posts and came up empty. Hope I haven't repeated anyone.)