Kindle Book Pricing

There is this series of light mysteries (Gaslight Mysteries by Victoria Thompson) that I read when I was sick in bed. The eleventh is due out on 4/2/09. I've read the first nine. Why not the tenth? Well, it is about the Kindle pricing structure.

When a novel is brand new it almost always sells for $9.99. After some undefined point in time, the price sometimes goes up. Then it often goes back down. If it is one of a series it will almost certainly drop. So the price for teh Gaslight books looks like this:

Numbers 1-8: $6.39
Number 9: $7.19
Number 10: $14.37
Number 11: pre-order for $9.99

Now, I expect that number 10 will fall to something like $7.19 when number 11 is available. I had hoped it would fall before 11 came out, but as that is just 8 days away, I'm not hoping so hard anymore. I've pre-ordered number 11, and I wish that I could put an order in for number 10 at the reduced price. It would be like any other pre-order, except I wouldn't know the date. I would just tell Amazon that the day that book falls to a price below $7.50, charge my account and send it to the Kindle.

It had never before occured to me that an on-line retailer should do something like this. The Kindle though makes buying books so easy, wouldn't this just be the next step?