Currently, the black velvet hair tie as worn by Kate Middleton is available at J. Crew Factory for less than $10.00.
Also available online from J.Crew.
On November 21st 2018, The Duchess of Cambridge stepped out for the day in a recycled double breasted Vine colored blazer and skirt by Paule Ka for a visit to the Psychology and Language Sciences Division of UCL.
The thrifty duchess has had the ensemble for six years and has worn the look on two previous occasions. For this outing, Kate also wore her hair back in a high ponytail with a J.Crew Black Velvet Hair Tie.