Adding More Fish ??

I am thinking that it would be nice to add some more fish, but my budget is a bit tight at the moment. I can probably afford to spend about $50 total on more fish. I have been looking on Aquabid, but haven't found a lot in my price range (once shipping is added in). I would probably like to add to the species I already have so that I have at least six of one species in the tank -- so I could get some breeding going.

Or I have also been considering the Tanganikan killifish -- Lamprichthys tanganicanus. These were made available recently on Aquabid, but far too many for me to deal with (20!!). I might email the seller, who I think actually sells fish on this site, and see if he'd be willing to ship fewer fish. Something tells me he won't as his minimum order advertised in his site is $75 -- far beyond my current budget. Sigh....