Zoro (or ZORO) is a subsidiary of
Grainger; can buy from their website or on eBay (you need to check both for the best price). Many times Zoro is cheaper than Grainger or has items that Grainger doesn’t sell. Also, once you register you get free shipping (at least in the U.S.) over $50 and after ordering get monthly coupons for up to 20% off just about anything (including Starrett).
Grainger is good in my case because there is a nearby branch and if you have an order shipped to the branch you don’t pay shipping. I have purchased metal from Grainger (drop shipped to the branch from Online Metals) for less than buying direct (OK, material cost was a little higher, but total cost was significantly less).