Mmm… some thoughts on alternative rust removers:
Evaporust costs about €50 for 5 L here, it consists of < 16% chelating agent ( the exact type is a well guarded secret), <1% detergent and the rest is water.
Citric acid is frequently suggested as a chelating agent but it will chelate (make soluble) iron as well as iron oxides so you shouldn't leave iron in it too long.
A good chelating agent for iron oxides is oxalic acid which costs about €8 for 1 kg on line in powder form, more than enough for 5 L of rust remover just add a few drops of washing up liquid as a wetting agent and you should have a good rust remover.
As for vinegar, I'd save it for my chips. It is not a chelating agent, the acetic acid it contains will make ferric acetate with rust and that is only moderately soluble in water.
Oxalic acid is a relatively mild poison but I wouldn't drink it. It is used as an antidote to lead poisoning.
Russell