So, forgive me if it's already a thing, and I'm completely blind but if not;
I feel like a button to show all the recent additions would be pretty cool, and possibly the ones that recently came in stock or something. That way when you've got guitars added onto the store that haven't been put into any category (aside from forum only deal ones of course), you can search newest, and see anything new that's been added, which is always cool to see.
That and seeing ones that got updated to have stock in/ all in stock items or something with the ability to sort by how recently they were brought into stock could be cool as well. Either gives you an option to see new kits, or fairly popular ones that have come back kinda dealio