I'd say you're looking at $2K+ to get everything in a 2x72 machines that is "ready to go".
There is no "one size fits all" when it comes to attachments and accessories for a new grinder. I'd venture to say that a flat platen, 8" contact wheel, and a 3/4" wheel, with a small wheel attachment would cover most situations/needs you'll encounter. Beyond that, other attachments are there for special needs/situations, or to make certain things convenient for the user.
Here's one of the main reasons I encourage saving and buying a 2x72....... when you spend the money on a 1x30, 1x42, 2x42, etc. That money is GONE....meaning you will never recover it if you decide you want to sell. When it comes to a "name brand" 2x72, you can keep/use it for a decade, and if you decided to sell, you'd get nearly as much as you paid for it.
Having been in your shoes, I know it's a lot of money, but if you have intentions of making knives for any length of time, it will quickly pay for itself. In my opinion, NOTHING will improve your knives more, or faster than a good 2x72" grinder.