The Boundlessskill.com API is now live. Documentation can be found here.
There is no authentication required for requesting information. If you would like to use the API to update the items you buy and sell in your shop see the OP with instructions on getting your shop added to the site.
If you find any bugs or need any help setting up your application to use this API please contact me or post here.
And check out @Lynxdragon project for a use case of how this API can be utilized.
https://forum.playboundless.com/t/item-price-estimator-live-market-estimations-provided-by-boundlessskill-com/22073