Sorry for the snark. For the items mentioned in the GP (strollers, etc) where there are a few well-known brand names/models, CL is going to be very hard to beat:

-pricing is rational and stable. In such markets, people just know 'what stuff goes for'. -where the savings of buying used is >$100, then the transactional costs of an email, a couple texts, a trip to the ATM, and a short drive are worth it to a lot of people. -no taxes, fees, waiting for your money, account signup, email subscriptions, app downloads, etc. etc.