The most successful online marketplaces today facilitate relatively simple transactions. There’s eBay and Etsy for buying/selling goods, AirBnB for short-term accommodations, and Uber for local transportation.

While reputation mechanisms (i.e. user reviews) play an important role on these platforms, the price tags involved are typically low enough that customers are ready to deal with strangers over the web. But, it can be a different story when someone is looking to spend $10,000 vs. $100.

There’s an enormous opportunity for marketplaces to emerge that handle high-value, complex transactions. However, to find success, they’ll need to make customers feel comfortable reducing the high-ticket purchase and/or complex deliverable to a few clicks.

Today, we already see marketplaces for more complex transactions… for example booking a location and photographer for your wedding (www.weddingful.com), hiring a web designer to create your next mobile app (www.ooomf.com), or finding short-term rentals for pop-up stores (www.storefront.com).

However, many of these sites currently work more as a lead generation engine than an actual marketplace and / or the platform needs to act as a hands-on broker to facilitate these transactions between participants. To realize the full potential of the opportunity, marketplaces for complex transactions will need to move virtually all of their transactions online by taking care of a few things:

1. Provide more information upfront: If you’re buying a book online, the ISBN and a rough description of the condition is usually enough information for you to feel comfortable making the purchase. But what about booking a wedding photographer? In this case, you’d want to see his/her portfolio, numerous reviews for previous clients, and possibly a write-up of the photographer’s approach and style.

2. Standardize traditionally unique transactions: Professional services companies are increasingly looking to create boxed offerings that include pre-defined scope, pricing, duration, deliverables, results, and other relevant parameters. The “productization of services” helps speed up traditionally lengthy sales cycles, and enables customers to complete complex transactions in a few clicks.

3. Provide more help to the inexperienced buyer: In many cases, buyers will be considering certain purchases for the very first time. In these cases, a marketplace will need to help guide buyers through the decision-making process. For example, oomf offers a project planner/cost calculator to help first-time buyers understand how much it will cost to make an app.

4. Reduce risk: Just like online retailers have found success via free shipping/free return models, transactional marketplaces also need to reduce risk for the buyer – such as by offering full money-back guarantees with purchase.

We still have a long way to go before complex transactions will completely move online, but I’m optimistic that some savvy companies will figure it out. In the meantime, consumer trust in the Web and online transactions will continue to grow. We don’t know who the major players will be, but this will be an interesting space to watch.