Engineer gobies/convict blennies are my favorites definitely not on the high price range, but not always the most visible fish and not condusive to unstable LR piles. I'm mainly fascinated by the behavior. Clown gobies, although a PITA to feed sometimes, are also great little characters and not too expensive.
The Okinawan Goby, Clown Goby, sand sifters, tangs (sohals like navs), dwarf lions, anthias, cardinal fish like P. kauderni and the Pyjama Cardinal, but my most desired, sought after, and eventual fish, Powder Blue Tang..... (An LFS had the first one ive ever seen alive here in Adelaide SA, and im sure the price tag is going over $AUS 300
Wow. These price differences really shock me. A know a bloke in another state who bought 3 PBT's before he got one which has survived. I dont think I could afford to do that for one species.