Hi All,
I happen to be a Web developer who does some work for these guys. Back in February the site had managed to get indexed by Google - and many of you found it - before they intended. The site and its pricing were still being updated. I admit the site still needs a little love, but they are very much a legit company. If you are in doubt of a price that seems "to good" - just give them a call. They can be reached at 877-MY-HYDRO or 877-694-9376 and they have live chat -albeit spotty. If you think they are over priced, I know they have a price match guarantee.
If you see something messed up - like a broken product or a 0 priced item - please - help them out. Shoot 'em email to them or use the contact form and let them know. As they guy who is going to have to go fix it sooner later - I implore you - be kind while they finish working the kinks out. They do have a huge selection of product and a pretty decent amount of grow info.
Regarding coupons - since I built their blog and help them maintain it - I happen to know they will be regularly posting coupons up there. I know they have a 10% off Advanced Nutrients, but it ends tonight. I don't know what the rules are here for shameless plugs - so I hope I haven't gone too far. If you want the coupon, hopefully you can find it on the blog.