"From a business perspective we decided from the very beginning that we would we would never IPO, and we would never sell to a bigger company." -- Yancey Strickler

Kickstarter just might be the hottest stock that everyone wants to own -- but can't. Founded by Perry Chen, Yancey Strickler, and Charles Adler in 2009, Kickstarter has grown into the giant of the crowdfunding movement. Over the past six years, it's routed $1.87 billion in financial backing from would-be consumers to would-be entrepreneurs.

A question mark on a piece of paper on a wooden table

Image source: Getty Images.

Over that time, Kickstarter has funded more than 90,000 projects, enticed 9.2 million people to fund those projects, 2.8 million backers to fund more projects, and turned 37% of its users' projects into actual, tangible products. In the process, Kickstarter has also collected as much as $95 million in fee revenue to run its business -- with 28% of that revenue collected in 2014 alone. 

That's one fast-growing business.

Seeing green
And yet, that same year, 2014, now-CEO Yancey Strickler famously promised that he would "never" sell the company he helped to create.

But what if he did? How much would Kickstarter be worth?

Red light, green light
Trying to figure out Kickstarter's worth today may seem an exercise in over-optimism, but stranger things have happened than a Kickstarter IPO. In 1999, we here at The Motley Fool published our first list of nine companies we wish would IPO (so we could buy them). Most of these companies had steadfastly insisted they had no plans to ever IPO -- but three of them wound up doing just that.

Green with envy
Its CEO's best intentions notwithstanding, Kickstarter could end up IPOing, too. So, what might the company be worth if it did?

Calculated from its standing start in 2009, Kickstarter's growth to perhaps $95 million in revenues through 2014 works out to... let's see here... $0 in 2009, divided into $95 million in 2014, and take the fifth root of that, equals... infinite revenue growth per annum.

That's not very helpful. So instead, let's fast forward a few years and see how Kickstarter's growth leapt out of the gate:

Data source: Author's own estimations, calculated from data released by Kickstarter.com. Not all pledges are ultimately paid out for successful projects. Unsuccessful pledges would not have generated a 5% fee for Kickstarter.

As you can see, 2010 was the first year Kickstarter saw appreciable pledge activity on its website (just under $28 million). At the 5% fee that Kickstarter levies on pledges, even assuming all pledges resulted in successful funding for projects -- which they don't -- that would work out to, at most, $1.4 million in revenue for the company.

Still, assuming generally steady levels of success on funding efforts, growth from $28 million in pledges in 2010 to $529 million in pledges in 2014 implies a revenue growth rate of roughly 108% annually over that five-year period. 

That's pretty impressive. According to data from S&P Capital IQ, it's comparable to the revenue growth rates of Internet stars such as Twitter and Facebook. If we were to apply their price-to-sales ratios to what we estimate is Kickstarter's revenue, therefore, then...

The Twitter hypothesis
...at Twitter's 11-times-sales valuation, Kickstarter's $26 million estimated 2014 revenue might imply a valuation of only $286 million on Kickstarter stock. Or...

The Facebook theory
...at Facebook's richer 20-times-sales valuation, Kickstarter stock could be worth perhaps $520 million. 

That latter valuation is probably closer to the mark. Kickstarter, like Facebook (but unlike Twitter), is currently a profitable enterprise, and according to Strickler, it has been profitable ever since 2010. As such, it's worth a higher P/S ratio than Twitter gets.

The stock market reality
Investors hoping to get rich off an eventual Kickstarter IPO will probably be disappointed with these numbers. But they "ain't seen nothing yet."

After setting off on a wild ride from 2009 to 2013, Kickstarter is showing decelerating growth in the amount of pledge revenue it raises. In 2013, total monies pledged to Kickstarter projects hit a record $480 million. But in 2014, that record was broken by only 10%, with pledges topping out at "only" $529 million.

Why is this? Part of the reason may be that users are seeing alternative crowdsourcing companies pop up. Part of it may be disenchantment with Kickstarter's business model, where consumers provide all of the financing for a new business, only to see that business sell out to Facebook for a $2 billion payday -- and pay Kickstarter fans precisely bupkis.

Whatever the reason for Kickstarter's slowing growth rate, though, and whatever investors might ultimately decide Kickstarter stock to be worth, I personally won't be buying into the company unless and until we see Kickstarter's growth engine get a kick in the pants of its own.