Reddit mentions of Star Wars Omnibus: Knights of the Old Republic Volume 1

If you are looking for a continuity of collection type (all Epic Collections), this probably won't help you. But if you are looking for the content, the same issues are collected in the Dark Horse Knights of the Old Republic Omnibus Volume 1, which has more affordable resale options out there:

https://www.amazon.com/gp/offer-listing/1616552069/ref=tmm_pap_used_olp_sr?ie=UTF8&condition=used&qid=&sr=

Unfortunately I haven't read anything Darth Vader or Clone focused, but I can recommend a few other things if you are willing to branch out.

Star Wars: Knights of the Old Republic
This comic takes place just before the first KOTOR game during the Mandalorian Wars, and follows a Padawan, Zayne Carrick, on the run from fellow Jedi after being falsely accused of murder. He and a likable cast of characters journey and adventure throughout the galaxy while avoiding capture and seeking to prove his innocence. This is probably my favorite Star Wars comic, and it recently got the omnibus treatment.

Star Wars: Legacy
Set 130 or so years after the end of the original trilogy, this series follows the descendent of Luke Skywalker who has pretty much abandoned the path of the Jedi to be a space pirate. In this era the Sith have made a comeback throwing out the rule of 2, and the main character himself struggles constantly with the temptation of the dark side.

Star Wars
This is a currently running series by Brian Wood, and takes place between episode IV and V. So far, it has been pretty cool, and has done a good job keeping the characters accurate to how we remember them.

I've only read the first book, Commencement, but it was definitely awesome. If OP is interested, there's an omnibus coming out soon that contains the first five books at a more-than-decent price point. I'm definitely jumping on that one. xD