The answer is a really <big>BIG</big> <b>depends</b>.
Are you looking to purchase it from a reputable recycler?
Do they use reverse osmosis or ion exchange or distillation process for purification?
Do they use completely de-ionized, de-mineralized, de-chlorinated water to reformulate?
Do they use a high quality additive package to recharge the anti-rust, anti-corrosion, ph balance, and lubricating properties?
For the average user I recommend staying with purchasing new stock. A fully formulated coolant is best. It you buy concentrate, make sure to use high quality distilled water for blending.
-John