pricing varys quite a bit, i recently bought 2 a. aculeatus for $30 each asking price was $39 for 1, i have seen the same and simalar species between $49-89. then of course you have to pay for overnight shipping unless you can pic one up localy wich i recomend if posible as octos don't ship well, it doesn't take much ink in the bag to sufocate them. i drove 71/2hrs to avoid shipping mine
the best way to get your moneys worth is to do alot of reserch and learn to identify what species your looking at so you can be shure your geting a young animal that has some time left since their life span is only about a year you don't want to get an adult with only a few months to live(sadly this is prety comon). what makes this tricky is an adult dwarf is the same size as a babby aculetus except the dwarf only has a few months left to live and is mostly nocturnal wich isn't much fun unless you up at 3 am alot and like the way your tank looks under red lights.
when i was at ny aquitcs they had 4 octos and all looked to be the same species mostly juvinile to young adult, i was told he always uses the same suplyer so theirs a good chance you'd get an aculetus if you orderd from him, i would ask for the smallest one they have. the 2 that i bought are bolth doing well and i see them bolth allmost every day wich is great becouse some peapole go months without seeing their octos.
some peapole have a problem with the short life span but after keeping corals for 15yrs i have spen't alot more money on short lived corals that wer not nearly as cool a pet as my octos