There’s a digital comics sale on X-Men. As the X-Men Blue and X-Men Gold monthly titles wind down prior to the Uncanncy X-Men relaunch, there’s a~64%-67% off sale on the collections. Five volumes of Gold and four volumes of Blue (including a Venom cross-over) are $2.99 – $3.99. That’s fairly low for recent Marvel sales and it’ll get you close to caught up on this iteration of the X-saga
Here’s X-Men Blue.
And here’s X-Men Gold.