Let have a look at it though:
Pure administrator types:
Lvl 1 Expert class, same culture as you, DDC: 5
As above but a Master in administration: DDC 10
As above but High level, to max out adm bonus: DDC 20
Bland and boring and not at all in the spirit of the game, but the most efficient way for any ruler worth his salt to hire. Get the bland boring guy that is never late, never wrong and never gets killed.
Lieutenants:
Level 3 (Low level) Warrior, same culture, DDC: 5
as above, but Rogue or Fighter. Must be this to get the Lieutenant's bonus action. DDC: 15
as above but Weak Blooded, maybe an heir: DDC 20
as above but Ranger, Paladin, Bard or Cleric. These can cast Realm Magic, even if your domain can't, so are DDC: 30
If you want a Wizard you start at DDC: 35 for a level 3, with no masteries in skill.
Once we're up there, adding the extra 10 to DDC to get someone high level is trivial, and a +5 to get a skill mastery. That's DDC 50 for the best of the best.
I would love you to tell me that I am doing it wrong.
If I were to redesign Hire Help I would make levels much more expensive but reduce the "tax" on blooded, and drop the distinction between realm magic or not and True Magic or not.
Non-caster domains are currently never hiring a caster, even if the flavor would suit them. Similarly caster domains need that guy, and once he is in, they do not need another, barring deaths. The balancing of caster domains should be in the on-going domain balancing, not in a once-off expenditure to hire new characters.
You could the Blood to its +ECL value, so what you do is take lvl + Blood ECL and scale the DDC with that. Starting DDC 5 for Expert classes, DDC 10 for Heroic classes.
Adding a mastery skill costs +5 DDC as usual. Different human cultures are trivial in differences, no need for it to cost something here. Adding an Elf, Dwarf or Goblin should also only add cost if they come with a special ability/skill, else it is basically just flavor, and can be used to prejudice against the court by others.
Now the ECL stair does not have to be linear. Something like this maybe:
ECL = DDC 5/10
1 = +1
2 = +2
3 = +3
4 = +5
5 = +10
6 = +15
7 = +20
8 = +30
9 = +40
10 = +50
Now a level 1 Wizard is much cheaper, but a high level one almost impossible to grab of the shelf, and he is priced the same as a Rogue or Fighter, meaning that any domain can grab any class they want for increased flavor of their courts.
The new scale also entices more to grab that Hero class character and use them more actively for both administration and adventuring/lieutenant work. Less optimal on the admin part, but more vivacious domain overall.
All of the above is of course based on my assumptions and view of the world. The existing rule seems a bit divided between securing game balance and what is "right" from a non-balance point of view. I believe all we need to focus on in the rules is the balance part, and let flavor run wild.