Uppababy Rumbleseat for Vista $152 (Jordan, Emmett, Gregory, Henry, Denny, Loic), $160 (Henry, Jake)
Additional 15% registry coupon (completion discount) can be applied from Amazon.
Uppababy is having a sale for 20% off previous year model strollers (vista & cruz) including some accessories (rumble seat). Looks like sale is for all previous model strollers. This seems to be available from multiple retailers such as albeebaby[albeebaby.com], Amazon, etc. Sale is listed on main website: https://uppababy.com/ If you wait, Piccolino[piccolinobaby.com] baby should be updating their website with the sale prices and I believe there is no tax from there outside NJ. Also available at strolleria[strolleria.com].
The 15% registry discount (10% if you do not have amazon prime) is set up by starting a baby registry at Amazon and set it to less than 60 days to delivery date which would bring the cheapest colors down to $612. You will need to wait 14 days to use the registry discount if you don't already have a baby registry or registry discount active. More on the registry discount here[amazon.com]
It looks as if the completion discount will apply for even those sold by other retailers but fulfilled by amazon so It doesn't look like you need to order direct from amazon.