I am looking for a formula to help me estimate a target market's
adoption rate of a new market offering. Obviously, it depends on
myriad factors including advertising dollars spent, consumer
propensity to purchase the item, size of market, etc.

But are there any widely used formulas that anyone knows that could
help me to get a ballpark estimate?

Hello mhugo-ga

The derivation of the 'classic' s-shaped market diffusion curve is
explained in the material on 'Models: Market Response Functions' at
the following link

http://www.econ.kuleuven.ac.be/tew/academic/market/members/Kalyan/Session%202%20-%20Models2.pdf



You will probably enjoy an article on the "hockey stick" market
penetration curve to be found at the following link:

http://www.cedmagazine.com/ced/2001/0801/08cic.htm


There is an interesting article regarding staying on the optimum
penetration curve that refers to videocassette recorders, Hotmail and
the Apple Newton. You will find it at the following link:

http://www.bus.iastate.edu/demarie/courses/MGT512/SatWeek3(AM)/smart%20mover%20dumb.pdf

The search terms used were as follows:
"s-shaped curve" + marketing models

I truly hope the above is of some help to you.

Sorry I found the last link in my first comment got corrupted. Please
try this.

http://www.bus.iastate.edu/demarie/courses/MGT512/SatWeek3(AM)/smart%20mover%20dumb.pdf

Once more I'll try to get the above-mentioned last link to you
properly, this time in two slightly different ways as follows:

http://www.bus.iastate.edu/demarie/courses/MGT512/SatWeek3(AM)/smart%20mover%20dumb.pdf

( http://www.bus.iastate.edu/demarie/courses/MGT512/SatWeek3(AM)/smart%20mover%20dumb.pdf
)

I have notified Google Answers of the problem with truncation of the
link URL after the bracket within it. Meanwhile if you want to make
use of the link, please carefully fully select it starting with the
mouse pointer at the right hand end ("pdf"). Then copy it to the
window of your browser.