If I were a YC company suddenly getting $150K, I would set aside at least a small part of it for testing different user acquisition strategies and business mode

If I were a YC company suddenly getting $150K, I would set aside at least a small part of it for testing different user acquisition strategies and business models. Take as little as $15K and make that your testing budget, money you're not afraid to lose learning what works and what doesn't. Create a few different landing pages testing different price points, appeals, targeting different customer segments, etc. Or take the patio11 approach and create a few highly targeted mini-sites centered around a very specific niche or customer. Then test every traffic source out there, carefully documenting the traffic volume, CPC, CTR, conversion rate, CLV, etc from each one. AdWords, Facebook, media buys, buying backlinks, it doesn't matter. You're just testing. The goal when testing traffic sources/acquisition strategies is to move fast and fail as quickly as possible. And that's a lot easier when you're not constrained by a $10/day budget and worrying about every penny. Don't worry about getting an immediate ROI on that money just yet- you're paying for valuable data that you can show investors and use to scale your business. Don't think about the money as wasted- every paid click brings you more data you can use to refine your campaigns.