Hi, haven't sold any models on here yet myself, so don't know if this will be any help but my suggestions would be:
Increase the price of some of your models. This might sound crazy, but people searching might put a minimum price filter on because they want to pay at least say 20 dollars, as anything less won't be of high enough quality for them.
Fully unwrap your models whenever you can & include a photoshop template. I mainly produce packaging models & putting myself in the position of a customer it's what I would expect myself. Easy customisation is a good selling point.
Although you are aiming at the architectural market who will mostly use 3ds max & vray, if you can include cinema 4d as a format. I know you include fbx, but if all the materials are set up for c4d it takes away the extra time needed to replicate the look you have achieved with vray & max.
Always include polygon and vertices stats in your models. Helpful for buyers who have a polygon budget to stick to.
Quote your machine specs and render times for your more detailed models, so buyers know more about how it will affect their scene.
Very nice models & I hope they sell well in future!