ZBrushCentral

Question: Should i buy the 2018 Wacom Intuos or

Hello, so im a traditional sculptor and i wanna get into using Zbrush and 3D sculpting. so here is my question. i see Wacom in 2016 had a package where you buy the wacom intuos medium and it came with Zbrush core for free. so my question is, should i buy one of those from a re-seller on Ebay/Amazon/Walmart and if i do, does anyone know if the Zbrush core will be expired or not? im taking a risk buying it cause the pen the 2016 model comes with has 2K pressure sensitivity, where as the 2018 model has 4k, however it doesn’t come with Zbrush core, so what is the better deal? should i buy the 2018 model with the better pressure sensitivity, but no Zbrush core?
i already have Corel painter 6 or whatever the current model comes with so thats useless to me. but if the pen is that much better is it worth it? ive heard you can upgrade pens but im not sure if the model from 2016 is compatible or not.

thanks for any advice you guys can provide…