Greycat buggies are discounted (not 100% sure how long, i think just the weekend) for 7,500 UEC (normally 15,000)
https://robertsspaceindustries.com/voyager-direct/Hangar-Buggies/Greycat-PTV
https://robertsspaceindustries.com/voyager-direct/Hangar-Buggies/Greycat-PTV