I have found Metrea parts for sale for the first time at Bike 24, a German site. Prices are compared directly other Shimano pieces they have for sale. Not a comprehensive list.
https://www.bike24.com/1.php?content=13&search=metrea
FC 46-32 double is 151€, about par with Ultegra. This seems like a lot!
RD short cage is 31€, par with 105
Wheelset is 235€, 35€ more than the WH-RX31 for 105-level disks, 35€ less than WH-6800 Ultegra wheels
The flatbar shifters, calipers, and rotors are there, but not the flatbar brake levers, and no sign of the bullhorn brifters, yet.
Listed weights
FC double 1036 grams - compare to 670g for Ultegra CX, 3/4 lb higher is no bueno
FC single 912
RD short 281 - Tiagra is 260, 105 is 230, Ultegra is 195
Wheelset 1093+1287=2380 for QR version, compare 899+1093=1992 for RX31. Yuck! But the Metrea wheels are much deeper section.
So far on a weight savings per dollar basis it's not looking like a great deal. I hope we can get more pricing for a fairer comparison.