Rock Out With $$$ (Can I Get a Self-Pubbed WHOOP WHOOP!!)

I am a math(s) geek and probably always will be. I love numbers and how factual they are. Like any good scientist (yes, I also loves me the science), I pithily say, "The numbers don't lie!" If your math(s) are right, you have your answer!

So.

The fact is that I am in a situation where $600/month (600*12 = $7,200/year) is an adequate income for me. I understand I am lucky in a few regards:

1. I live with my fiance who only requires I pay my own bills and stock the house with food. (No rent.)
2. My car payment is less than $188/month. (Rock on Riley, I love my 2006 Chevy Aveo!)
3. I sent home most of my income while I taught in Japan - thus paying down my bills more than average.
4. I am smart with money (AND MATH(s)!)
5. I have implemented the Snowball Effect as pertains to bills, so I am ahead of the curve.

I am planning on selling my current WIP for $3.99. Let's round my royalties from that to a nice number - $2.50.

At $600 needed a month, in increments of $2.50 payments:
600/2.50 = 240 books a month must be sold
Per year:
7200/2.50 = 2880 books a year.

My goal is to sell 1000 books by December 15th, 2011 (of my current WIP). I expect to have at least 1 other book completed and up for sale before then.

If I assume 3/4ths of my sales will be from Book 1 (based solely on the fact that it will be sold longer):
.75*2880 = 2,160 books will have to be Book 1.

Hmm, that's still higher my 1,000 goal.

But, if I make my goal to sell 1k of Book 1, and produce 2 books, I can break it down closer to something like this:
Book 1: 1000
Book 2: 700
Book 3: 400
Total: 2100... getting a lot closer to providing for myself!!

This also assumes a continuous $3.99 price point for all three. That may not necessarily be the case, in which, I will have shorter works but probably more of them. So, if I were to say:
Book 1: 1000
Prjct2: 700 (at $2.99 ~ @1.75/book)
Prjct3: 400
Prjct4: 100
Total $: ((1000*2.5)+[(700+400+100)*1.75]=$4,600/year. That's more than halfway to my goal :)

I don't know what I'll write this year, or how fast I'll write. I don't know how good the ideas that come to me will be (but I pledge to discard the lame ones). I think it would be a shame if I couldn't produce one more book this year, awesome if I could produce 2 and amazing if I could do more, and still have the level of quality I expect from myself.

From my random math(s) ramblings, I believe I could be self-sustainable within 2 years.

I would like that very much :)

Addendum:
Robin Sullivan posted this insight over in the comments of Konrath's blog:
1 book - 10 / month
2 books - 50-60 / month
3 books - 200-400 / month
4 books - 1,000 / month
5 books - 10,000 / month

So, according to that, if I have 3 good books out, my theory holds pretty true! Two years ahoy!