Spree Pricing

A price in Spree 6 is always an amount plus a currency on a variant — there is no implicit "the" price. On top of the base prices sit price lists (conditional overrides), resolved per request from a pricing context.

Variant ── Price (price_) × n
             ├── base prices:  price_list_id = nil, one per currency  (what everyone pays by default)
             └── list prices:  price_list_id = pl_…, per currency, optional min_quantity (quantity breaks)
PriceList (pl_) ── PriceRule × n (STI: MarketRule, ChannelRule, VolumeRule, …)
            └── optionally owned by one Catalog (cat_) → audience = the catalog's assignments
Price ── PriceHistory × n   (base-price changes, for EU Omnibus)

Tax-inclusive vs exclusive display and VAT restatement live in spree-taxes.

Base prices: price_in / amount_in / set_price