I've ordered from marinedepot and Dr Fosters, no problems. I also purchase more sensitive stock locally. I haven't seen an online retailer who didn't offer to replace or refund for DOA or in the case of Fosters a 30 day 'stay alive' warranty. However, I do excercise what I consider common sense when ordering. If its 100 degrees out (Which it is where I live now) then why order online and put the animal through the stress. The same is true when its 20 degrees out. Styrofoam can only do so much, so if its hot as the sun out, I would shop local or wait until fall when you know temps for shipping will be more reasonable.
To fail to plan is to plan to fail.