You are wise to be considering Part 91 and Part 135 jet gigs (referring to US Regulations). I had (still have it) an ATP and one type rating when I got my first jet gig and my second employer sent me to Flight Safety for my second type rating. Pay and equipment varies widely, but the best operations fly new equipment and pay well. A really good Part 91 gig (new top of the line equipment, top pay, stable employer, good schedule, no airline travel) beats most airline gigs any day.

First, there is no such thing as a CPL. It’s not a ‘License’. It’s a Certificate.

Second, if you are only going to fly corporate flights, the ATP is nice, because it gives you lots of hours. But, IMHO, you are better off having the specific ratings needed for the company you want to work for. IE, rated in the bird you’ll be flying for them.

Third, as far as costs, firgure between $50 and $75 thousand to get to the level you’ll need to fly right seat as a corporate pilot.