Felt that this deserved its own topic. Ideas came about based on conversation on discord (thanks to those that were participating in that convo).
3 stage approach
Auction House (like ebay) - only offline vend. charge 5% fee on buyer and/or seller (provides zulie sink in order to gain global audience/listings).
Local classifieds (like FB marketplace/Craigslist) - no offline vend. Charge a small fee (1%?) to list on the local classifieds. Local could mean only the map you are on, the planet, or just the shops that are rendered in your vicinity. Have a searchable page or window to list the local items, but no option to buy. Instead, will have the map/shop name/coordinates.
Traditional shop - retains the current vending structure. default all vending to traditional shop, players must opt to list an item on local classifieds or post to auction house.
Everybody gets something they want. Ability to offline vend (but at a cost), still have traditional shops, but also add local classifieds to make vending/shopping easier.