I would probe the exact items.
"Shimano 105 drive components 27 speed with flight deck double shifters.
Shimano caliper brakes with new pads. "
On a 2018 bike 105 9sp (?5400?) means that the drive components are 12+ years old. It will not have been sold like this so likely the it was bought as a frameset and built up.
105 STIs (shifters) are implied but "27 speed" implies a triple. Why is a double mentioned?
Shimano makes many levels of caliper brake. What model are these? 105?
The aerobars are not for TT, they are for long distance comfort ie randonneuring.
The chainset is old as well - which is a good thing - and will be square taper (so a normal BB threaded shell).
Leather saddle would be expensive to buy but may or may not fit you.
I can't tell from the image what the wheels are: and the seller doesn't say.
Ti frames will hold their value better than others so I think people will pay more than 50% - if this bike cost 1300 dollars, then the frameset cost over $1000. And essentially, that's what you'd be buying. Is this really a 2018 bike? In what way?
https://www.pinkbike.com/buysell/2348419/
Full disclosure: I am about to build up (a minimally used) Lynskey Ti frameset to roughly this spec (of 9sp (non) groupset etc) so I know how much this non-vintage stuff costs.