I think the market is unreliable because it's always changing according to the current needs/wants of consumers. The Panama canal situation was a rare success and it just so happened that the market was reliant on the shipping services which basically gave large corporations an incentive to contribute to resolving the canal problem. Getting those ships through the canal without troubles was the most ideal situation for shipping companies and large corporations who relied on shipping since there may be other issues for them if the canal was no longer available to use.
Trading ecosystem services on the market would only work if the problem largely affects the current market and also affects those who are able to provide resources or funding so that they would actually want to solve the issues.