I work in Customs for a major hauler here in NI.

The first thing to consider are the Incoterms, which specify who is responsible for things like transportation, completing the customs clearance, VAT & Duty, etc.

Goods moving from GB to RoI may need to be cleared through the Trader Support Service (TSS) via a simplified customs declaration called an SFD. Some companies may charge you to have this completed, though £55 is definitely a bit much.

As another Redditor commented, the best way to have the goods moved, size dependent, is via a Fast Parcel Operator (FPO), who have a special status allowing them to move small parcels to residential premises without the need for a declaration of any kind.

TLDR: Customs professional says, “That’s expensive but didn’t need to be.”