To many people, including myself, citric acid, though technically an acid, isn't "really an acid" in the horible corrosive sense one would think of acids. Heck, many of our cleaning products are made with citric acid.
I looked at our company's MSDS on citric acid and find that it has the same NFPA or HMIS ratings as EvapoRust.
Instead of bidding on this product, you'd probably save some money by using Prestone Super Flush.
Evapo-rust is crap.
It is available in walmart around here, this is where I first bought it.
For a better rust eater, go with Naval Jelly. Ace Hardware (and others) sell a 10 oz bottle for about 3 bucks. Level 3 works great. Put it on w/ a paintbrush. It goes pretty far.
For bigger jobs, Tractor Supply Co sells a big spary bottle full of rust eater. It works pretty good too.
Naval Jelly is the best rust eater I've ever used.