When working on a double-sided marketplace how do you work out cost of customer acquisition?

Check out https://www.balancedpayments.com/ They are made for marketplaces. Airbnb CEO among others invested in them and they have some of the best pricing/payout fees. Also some good info on http://www.collaborativeconsumption.com/2013/10/08/online-marketplaces-are-hard/ One of Balanced Payments co-founders is writing this blog series on marketplaces.

At WP Engine, everything in marketing and sales is included in CAC. Salaries, commissions, coupons, direct advert spend (which you're saying you don't yet have), fees, travel and other costs associated with conferences, etc.. My advice is to err on the side of putting too much in CAC, because that helps you honestly understand the costs. Ignoring some costs just because they don't scale with company size or marginal new customers doesn't make sense to me, it simply means that certain components of your CAC you expect to get more efficient over time. Indeed, they had better! So measure it, instead of ignoring it. You also might find that some of those direct-spend channels are not as inefficient as they seem compared to things like SEO efforts. Or the reverse! All good things to explore of course. I'll also note that at $19/mo in the crowded space of CMS offerings you will find that very few channels will be efficient compared to the revenue you're generating. It sounds like you know that, and are dealing with it with "scalable" efforts like content marketing, however again you should be ruthless in understanding how those costs are really translating into orders and whether that's a financially sensible total strategy.

I always suggest going "uncomfortably narrow" initially so that you can really dial in the user experience and build liquidity first. Going broad will be tougher as there's too much noise to signal. Also, it's best to fake the supply side initially of you can to improve the buyers side first, then figure out supply & quality afterwards if customers are buying and you've proven out a demand strategy that will work.

To answer this, you need to have a working model for your customer LTV (Life Time Value). Most startups can't accurately estimate their LTV, so if you don't have good enough data, then building your CAC based on assumed LTV numbers can be fatal. In this case, it's better to evaluate your CAC costs based on the months of revenue it takes to recover the cost to acquire the customer, and ultimately this calculation should be net of any costs associated with providing the service on a monthly basis and, even more conservatively allow for a healthy degree of churn. Keep in mind that this calculation doesn't evaluate your true profitability only the capital efficiency of your customer acquisition spend. Hope this helps. Happy to talk this through in more detail and with more specifics to your business.

I like to separate your question into 2 sub-questions: #1 How do we determine which side to charge? #2 How much is the right amount to charge? On #1, my answer is that you can charge the side(s) for whom you add the most value. In your examples, Uber really solves a big problem for drivers, it's that they sit idle for a good part of the day, so are willing to pay a lot for new leads. (their alternative is no work) Consumers are charged more for the convenience of a private car but they are probably not so much willing to pay more for a taxi, even if they can hail one from their phones. For AirBnB, it's a mix, it's a way for landlords to monetize idle capacity which they are willing to pay for, but it's also a way for a renter to pay less than they would normally pay for a hotel. On #2 (how much), I like to triangulate a number of factors: - What's the maximum amount I can charge one side, while still being a good deal for them. - How much do I need to charge so that I can become profitable? (the economics are quite different if you charge 3% vs. 12%) - What are comparable services charging for substitutes/competitive offerings? I will just add that there is no formulaic way to determine pricing strategies (curated vs. open), and it's a lot more about what's the comparable and what the value delivered is. That's how I approached the question while deciding the business model at ProBueno.com (my startup)