A laptop like this would be a good place to start. It has enough RAM to not be terribly slow, and it’s expandable to up to 8GB RAM so if in the future you want to upgrade there’s always that option. While the Intel Celeron processor isn’t great, it’s something to start with.
By the way, if you need any help with the installation of Kali (or maybe a different operating system), just PM me. I went through the process when I was just learning about computers, so I understand it can be rough if you don’t know what you’re doing. :P
