First let me make it clear that I have never made a fortune on KDP but you dont have to have invented the bomb to be a nuclear physicist.
The Big Secret...
KDP has got to be the most easily gamed system online right now but before I reveal the secret, some facts...
30,000 - 40,000 = 1 copy/day
20,000 - 30,000 = 2 copies/day
15,000 - 20,000 = 3 copies/day
10,000 - 15,000 = 4 copies/day
5,000 - 10,000 = 5-8 copies/day
2,000 - 5,000 = 10 copies/day
1,000 - 2,000 = 15-20 copies/day
The 1000-2000 rankings are more like 40-50 sales per day.
Edited: A #2000 ranking is ~30 sales/day. A #1500 ranking is ~40/day. A #1000 ranking is ~50-60/day. And these are rolling averages.
126 copies of the book and achieved my best sales rank of #333.
These days, I’m selling between 10 and 20 copies a day, and my sales rank fluctuates around #5000 to #9000.
15 copies a day, and my rank was around #5000
Ok so this means...
A $10 book ranking around 4000-5000 on Kindle can make $1000 per week profit
And that means...
I would guess that in reality less than 2000 books make $1000 a week or more on kindle out of 1,000,000
So kindle suddenly doesn't look quite so phenomenal in that light
Basically its a game to get a ranking under 5000. Just find niches you like with best sellers ranking below 5000 in the kindle store
SOOOOOO.... USE FRICKEN PPC
yes cheap clicks from PPV, POF, facebook etc will give you best seller status over night
Break even on your PPC and you cream the $$ off Amazons best seller traffic.
That in a nutshell is the secret to KDP today - a year from now KDP will be fried.
A two pronged approach is best on KDP - high quality books - and shotgun public domain - but you should push it all with PPC
KDP books can also be sold on createspace, nook, clickbank, ibookstore, tradebit, kobo, scribd, docstock, google, B&T etc - screw select
KDP is just another avenue - not the end game