I get asked frequently where I source my material and components and as a consequence I will add a few posts to this category to help others finding special items. Generally I buy 95% of my components and materials from Ebay with sources mainly in Hong Kong and mainland China. Rarely I buy something through Ebay from an Australian source. All the items which are offered on Ebay Australia are available directly from China for a fraction of the price. I also use sources in the US which are faster than China and mostly faster than Australian sources from over east.
I also buy lots through Ali Express and sometimes I go to Europe with my searches.
Here is a website I found some time back for reasonably priced DC contactors.
I had a double pole latching 100A contactor custom made in China for $29.95 purchased through AliExpress. Unfortunately they do not offer this service anymore. Latching contactors for higher currents are not that easy to find at a reasonable price. I use the 100A contactor to isolate my solar charge input from the battery.