Lots of people have good luck with liveaquaria. The only downside IMO
is that the only shipping option is $35, so shipping costs really get you, especially when some fish can successfully be shipped priority. msjinkzd.com also has a good selection of nano fish and inverts, and her stock quality is amazing. She doesn't ship fish priority either, however she has the fedex 2nd day option, which is pretty close in comparison to priority.