I tend to agree with most of the points already presented and am in favor of supporting local business, so I'll just add a few comments.
When it comes to the critical life support gear (Reg, BC,Computer, Mask, etc.) and even some of the lesser-critical but important gear where fit and comfort are important (fins and exposure suits), I wouldn't consider online. I would use a "LDS" that I can trust and can get good advice from as well as "try on" gear with.
Our LDS spent an hour with us trying on gear and actually talked us out of some of the more expensive gear and found us better value alternatives for the type of divers we were planning on being. We definitely paid more than a discounter on-line, but it was WELL worth it.
Now when it comes to the non-criticals (gloves, weight belts, accessories, clips, gadgets, gear bags, even knives and lights), I would say you can get some great deals online. I've used diversdiscount.com and diversdirect.com and have been very happy --- but the lions share of my $$$ investment went to my dive shop.
All that being said, there is a reasonable markup on equipment, and there is gouging. Not knowing particulars, $180 vs. $80 does sound like a little bit out of the ballpark. But again....weigh the entire cost of the experience including advice and the training provided. And if you still feel "ripped off", then find another local dive shop.
Good luck.
:doctor: