I'm building a marketplace to sell second-hand collectibles (like miniaturas, cards, etc...) and i'm exploring the different monetizing models to approach. Charging a % per item sold seems like ebay and they already sell this kind of stuff, i need a more freemium approach... Could you point me to some more models and information?
Your pricing model should hinge on the fact that the perceived value of services should outweigh the cost associated with it. You can consider looking at online marketplaces like Craiglist, Kijiji, Airbnb, etc to understand various types of business models. However, the approach shouldn't be based on what others are doing. Rather, you should understand your niche, values associated with the niche, and adopt appropriate pricing model.
Invest your time in designing the business model for your startup, followed with reviewing it vis-a-vis other models.
Need help with business model? Feel free to reach out.
Here are a few:
Shopify: First 14 days free, then a transaction fee
StoreEnvy: Completely free for your own private shop, but anything that is sold from their marketplace, they get 10%.
Etsy: $0.20 to list an item, 3.5% transaction fee.
When Etsy started, listing an items was free (just a very small transaction fee when an item sold). You want to get a big enough marketplace to attract buyers, so this is a good idea.
Perhaps you can think about adding optional features for buyers and sellers as an alternative revenue stream.
Services like Ebay and Amazon steal so much of your revenue in listing fees and selling fees that it can make it very difficult for your business to succeed. However there is a reason that they can charge you, and that is because of the marketing of users they have. Unless you have the traffic it can be difficult to get your products out there.
In your case of second hand collectiables - I would look at sites like WIX or Bandzoogle - that for a monthly set fee $20 you an use their templates to create your site. The massive bonus being that you can upload as many products for sale as you want and they wont even take a cent of your sales.
But this doesn't resolve your problem of traffic - there a number of strategies you could implement, the first I think would be using social media to connect with very targeted users. Directing your marketing to your target market is a key to success.