Mike at Finatics has big ones for cheap. They cost 20-30 bucks at petsmart for a 1 incher, you go to Finatics, and you can get 5 incher for about 10 bucks i think.
I have 3 Eupterus available if you are interested. The largest one I have is around 6-7 inches and the smallest is around 3-4 inches. I raised them from when they were an inch in size. they have nice big sail dorsal fin, and its in with my 7" Elkindo Red. I can let him go for $30.00 and $20.00 for thwe smaller one, plus delivery of course. but he is a nice specimen. I will post some pics if your interested. Where are you located? I am in the Toronto area.