http://www.allegorithmic.com/substance-ue4 The plugin for the UE4 just came out, if that helps at all. I haven't gotten to trying it yet, but at least you don't need to recompile the engine now to be able to use it.
Might be worth having a look through this thread. Seems like he's only released a handful of his UE4 matcaps so far but I think he's planning on releasing the lot in the future: https://forums.unrealengine.com/showthread.php?13501-Matcaps-for-UE4&highlight=matcap
Just go with UE4 for now, $20 is the lowest you will have to pay. TB1 + TB2 are amazing, but depending on what you are doing it might just be more cost effective to go with UE4, plus you can deal with more kinds of content. I still recommend picking up TB2 later on down the line though.
I've watched some tutorial vids for both UE4 and TB2 and yeah, I've got to agree that TB2 is more user-friendly, but UE4 doesn't seem too much more complicated. Updates for UE4 are $20, but the latest update seems pretty stable and good enough to render scenes with. Even if I did update everytime, that's 5 updates, and…
While I agree that Toolbag is easier to use, it seems to me that showing you can put together a good looking scene with UE4 would be an advantage when looking for jobs, especially if said studio uses Unreal.
TB2 is much more user-friendly and faster to get the hang of. If all you want to do is show off the materials and models, and not fancy shader effects, then I'd rethink TB2. It is more money up front, but if you were to need an update for UE4 then that's another $20 each time.
If you're doing large scenes I would definitely pick up UE4. If you're just using it for single props or small diorama scenes I would just use Marmoset Toolbag 2. Substance Designer now has the Yebris rendering engine as well. That might serve your needs if you're just needing it for single assets and are really wanting to…