Never mind that they're so "cute".... I hope u know they're brackish water fish and as they get larger, they require marine conditions to thrive. If you're prepared to set up a tank for these brackish fish, who by the way get up to about 20cm tall(!!) (BIG FISH!!.... anything less than 4" tank is unsuitable), then M.argenteus can be easily gotten and cheap. Most LFS can't keep them propperly (they keep dying in their tanks because of incorrect water), hence why few stock them.

I can get u M.argenteus any time.... question is are u prepared to propperly house the fish?