I have purchased cast iron kettlebells from https://mirafit.co.uk/ and also https://www.strengthshop.co.uk/ if you hunt around sometimes you can find discount codes online.
Edit - USE CODE: STRONG15 on kettelbells for 15% off on strengthshop
DFW is a great program. The author Geoff Neupert has written a few well respected programs https://chasingstrength.com/products/ I do find his website hard work to read.