Unfortunately, crankbaits don't build themselves. Think about how many hands that lure has to go through before you purchase it and tie it onto your line.
Someone has to put the bait into the mold machine
Someone has to put the weights/rattles in the lure
Someone has to paint and clear coat the lure
Someone has to put the split rings and hooks on the bait
Someone has to test each bait to make sure to swims properly and passes QC
Someone has to place each bait into the packaging and seal the sticker seal
Someone has to place all the baits into a box for shipping
Someone has to be the carrier (USPS, UPS, FedEx)
Someone has to unpack those lures for storage
Someone has to either hang those lures on a shelf or package them up to ship to you (and repeat earlier carrier step)
Keep in mind, none of the above takes in account for R&D, damaged baits in the manufacturing process, lures that fail QC, promotion and advertisements, attending trade shows and events, sponsorship of tournaments and professional anglers, warehouse costs, insurance, etc...
And at the end of all of that, you end up with a $4.39 cent wiggle wart from websites like TW.