Bed Bath & Beyond[bedbathandbeyond.com] currently has a sale on all Neato Botvac Connected Robot Vacuums. The standard 20% off coupon Bed Bath & Beyond sends out in the mail will also apply to the Neato line. Orders over $39 ship free.
If you are having issues obtaining a 20% coupon, try opening a new browser window in incognito mode. If you are a first time email subscriber, you can put your email in to obtain a coupon.
I personally purchased the D7, although I have read that the D6 is very similar. This is a stellar vacuum for use on carpets. I plan on following this up with a SquareTrade warranty due to longevity concerns.