With the new layout of BC, would it be possible to implement something similar to pinkbike.com's buy and sell section? You have a list of continents and you can pick which continent you are interested in buying from. You can leave it at that and browse through the items for sale or you can narrow it down into country within the continent. Within the country you could also select Province/State and depending how centralized some areas for buying and selling are, within a specific area.
For the items being listed for sale, you could have the categories for things like:
They can all be subcategorized into their own correlating brands as well.
A price range selection can also be implemented to ease the search for some people to find something within their budget.
The seller can also list out if they only want to sell locally or if they are willing to ship locally/nationally/internationally and the buyer has the option to pick if they want to deal internationally and whatnot with the shipping costs. If people want to trade their items or want to sell and/or trade that can also be listed out.
It seems to me that a lot of people find the buy and sell section on BC to be a little confusing especially those that aren't from countries which badminton is popular. Everytime I go on BC buy and sell, I usually see mostly Malaysia and Singapore rackets for sale and using the search function results in even more confusion. It may be a lot to implement buy I would hope to see the continent-country-province/state categorization put in place to make everyone's buying and selling a bit easier.