a betta or some shrimp imo... ive heard of people putting platies in that small of tank as well
Search the site for nano fish. Neons won't works but 4-5 embers might.
I don't think neons are a good long term choice for a 5, for activity levels if nothing else.
Honestly, a 5 gallon is a good tank just to keep around in case you need a hospital tank or something along those lines.
Maybe ember tetras and red cherry shrimp on a black background and black sand?
Shipping can be expensive, but the quality is usually fine. Remember that all the fish in fish stores were shipped there, many with a lot less love and care than they deserved.