Hope you get a good answer on this one, perhaps posting the plans or inspiration photos would help nail down some costs.
https://www.homewyse.com/services/index.html is a tool that you might use.
Perhaps somewhere between the price of shelves and base/wall cabinets might be a marker.
Only one wall of bunks was built from our designs, as I warned Owners that furniture will be less costly, perhaps more stylish and room more convertible for a) resale, b) kids that grow up or prefer to leave a bunk.
The one built was like you described with steps-to-nowhere between the pair or pair for access.
Storage was below and each had reading lights + outlets for optional/future personal "787" hung TVs.
I don't have the cabinetry bid to be able to give you a clue as to cost.
Those prices seem high compared to the furniture options, e.g.
http://rb.gy/5w95jhttp://rb.gy/4msinhttp://rb.gy/2hluabut then I think $70k for a new 2022 truck is criminal, so what do I know?
Ten words or less ... a goal unattainable