These are more commonly sold under the name of Rainford's goby or rainfordi goby.
These guys are very timid and peaceful, they get bullied pretty easily. They are also great algae eaters. I have had these little guys do a pretty good job at keeping nuisance algae cleaned up. They will eat frozen food pretty willingly, I start with small mysis and similar but they learn to eat formula pretty quickly. They are fragile but fairly hardy and seem to survive shipping pretty well - all around good fish even for smaller aquariums.
I'd say the average price for one of these is in the 20 - 25 dollar range although we have sold them for as little as 12 to 14 on special (like on the buy it in the bag specials we have done in the past.)
Another one to look at with almost identical requirements is hectors goby. another very cool small fish.
If you can't find one, let me know and I'll see what I can do.
Joel