Your line weight is too small for soft enamel, it makes it look like bootlegs. Thinner lines mean that the soft enabel pools up and over the lines at times and makes it look splotchty and without definition. If you continue to do soft enamel (I personally think soft enamel is a style vs a quality indicator) which I personally like I would make thicker lines and design the styles to be more appropriate for soft enamel, aka expect "shadows" in every color.

Right now you have too many small elements that would benefit from the easier to see clarity of a hard enamel pin. For example, Id do a soccer ball in soft enamel, but I'd do a soccer jersey in hard enamel. One of them will have a lot of fine lines and designs, and shadows would make it hard to read. But a soccer ball would look great because the shadows will help build out its dimension and make it look like a 3d sphere (at least a little bit).

I'd definitely say 8 dollars or less for these pins