I get three answers
1. Not allowed ( manufacturer/vendor regs)
2. High Touch sales, "anyone who was over worried about price isn't likely a buyer/good match" real buyers know the price range and we need to customize/vet the buyer
3. Highly customizable product that they cant or won't invest into making possible to pre-price online, probably wont get added to a cart and shipped or sold without a buyer wanting to actually talk to someone)
( for example, a 150k Caterpillar with various attachment options)