What connector type is this 3 pin connector
This is a JST EL connector.


It doesn't seem possible to get them from my usual sources. However, they do appear to still be made, and you can buy them directly from JST on their website, as long as you're willing to buy a lot of them. The one you have in particular is ELR-03V, which costs ¥35 (about $0.33 US with current exchange rates) each in quantities as low as 10. (for just the housing, contacts are a different story)
Its mating connector would be the ELP-03V, which apparently you can only buy in quantities of at least 500, for ¥4.20 (approx. US$0.04) each
The relevant contacts are about ¥7 (approx. US$0.07) each but there are too many variables (what size wire you want, in particular) for me to bother linking to individual contact pages on JST's shop.