If new 3GB 1060s are all significantly cheaper than 6GB versions and come with good warranties, go for it, unless you're set on mining Ethereum. 2GB cards are already obsolete (without fancy tricks with loading the DAG), and it's only a matter of time before 3GB cards are as well.
1060s generally do quite well on Zcash, and are also quite efficient with electricity. 6GB versions generally perform better, but that's usually not significant enough to justify a large price difference.
Newegg was selling some recently at $230 (including US shipping)
Amazon (US) expects to restock them within 1-2 weeks, although I'm not sure if they will readjust their prices.
General tip: If possible with your budget, avoid the 1060s with single-fans that are oriented towards users with much smaller cases. Blower-style coolers are fine, but not the compact versions with a single (non-blower) cooler. They'll run hotter, and remember that you plan on pegging them 24/7.
Example:
Avoid
Unless they are significantly cheaper than those with dual-fan or blower coolers.
With only a few cards, those single-fan cards will probably be okay. Otherwise, avoid them unless you want to rig up some extra fans.
