Cable budget in a rig

As much as needed until you reach the point when you no longer hear any meaningful difference going higher.
And when you buy used you can sometimes get lucky and have $2.5k cables for $600.
It also depends on the complexity of your system. If you have one source component and integrated amp - that's one set-up, and if you have three source components, separate transport and dac, separate phono stage, preamp and power monoblocks - that's something different.
I could live with one of my $500 interconnects on $1200 phono stage but what do you know - I have $1500 cables on it and the $500 one is in the closet for rare cd player use, which is also in the closet. My speaker cables cost new as much as the speakers, and power cord for the integrated amp more than the amp. All bought used except two pairs of interconnects. Now all my active components sound as good as they can, I believe. Soon it will be time to build a completely new system.
However, if you want the simplest answer to your question, I would say 20% new, generally speaking. Tonearm cable is very important if you think about playing records or play them already.
Each cable is a component and all of them much more so.

This is one seriously expensive system. Cost will also depend on the length of cables and power cords, and also on your hearing. In my view, really good interconnects and power cords start at about $1500 and speaker cables at about $2000, digital cable I am not sure, probably $1000 or so. But you should listen if you can, there is no reason to pay more than needed. One brand approach is simpler but not always the best. Some say that if one runs balanced XLR interconnects, especially if the equipment is fully balanced, the cables can be of lesser quality and lower price. Can be in some cases but I don't take it as an axiom. Sometimes $500 cables are overpriced and $1500 are not, and sometimes both are about right, considering overall crazy prices of good stuff.

You didn't tell us anything about your coming equipment. What is it ?

Great plan. Speaking of transistor and hybrid electronics, at this level I too would consider Ypsilon, Gryphon and Swiss brands. I would add Lamm to this company, and I am sure there are others I am not aware of. I probably would not combine Nagra with Luxman but who knows ? How did Thiels sound with Ypsilon ?

Don't know about the others, first cables to try with Gryphons are Gryphon cables, then maybe something else too. With Ypsilon - Stage III Concept cables.

Wow, you are thinking in the right direction. I would also add Studer deck and some turntable to it. Never mind.
And what are your speakers going to be ?

I personally wouldn't buy anything before auditioning Ypsilon and Gryphon, but that's me. I also happen to like both designers, watched a number of videos on youtube. Read about them too. If a designer makes no impression on me - I don't even consider his equipment, especially at this level.

But you mentioned DarTzeel and Nagra, both Swiss. I have never heard of Aries.