Biggest problem in priority storage area

[Nukejet]

I reeaaaaaaaaaaaaally hope that pawns transfer goods from the low priority storage area to high priority area after quantities in high priority area drop below certain number, rather than Filling it to full every time.
  For example, the max limit of high priority area is 3750 ,minimum is 2000, the pawns transfer good only if the qualities drop below 2000.

[WhiteDevil]

try using the lwm deep storage system to pseudo-achieve that.

if you need many, many hundreds of an item at a single cell location, build a pallet box
if you need about 200 quantity, build a double shelf
(and so on..)

notes on lwm deep storage:
it does not modify or enhance max stack size of items, it just offers more choices of storage structures (ie: boxes, weapon racks, fruit barrels, etc)
all storage items function as a customizable storage zone

[zgrssd]

I reeaaaaaaaaaaaaally hope that pawns transfer goods from the low priority storage area to high priority area after quantities in high priority area drop below certain number, rather than Filling it to full every time.
  For example, the max limit of high priority area is 3750 ,minimum is 2000, the pawns transfer good only if the qualities drop below 2000.

For really high priority - aka raw material for crafting and cooking - just use shelves right next to the workers. Between 2 and 150 units fit into 1 shelv.

To my knowledge the base game has no way to define a per-storage limit, orther then picking only 1 resource managing the overall size of the storage zone.

[wwWraith]

Rimworld Search Agency allows to set a min per-spot limit to transfer.
Other useful features exist in Storage Tweaks.

[LWM]

I use Deep Storage with Satisfied Storage and it works quite well.  Satisfied Storage or RSA alone would also work for you.

(There's a version of RSA that should work with deep storage, but it's not on Steam yet, if you get your mods there)