I try not to place a specific $$$ value on grills as it rubs people the wrong way. However, enough yellow kettles have sold publicly that I am comfortable saying that this grill as-is is worth $2-250+. The value will vary on the specific condition of the parts I don't see but that kettle looks pretty clean to me with no major dings in the middle of the lid or bowl. The location, willingness to ship, how good the person is at cleaning/marketing their kettle, and season will also play a factor. That $900 yellow was an anomaly.
The "what is my yellow worth?" topic pops up every once in a while so I'd check them out if you haven't already. This thread has a pretty good discussion: weberkettleclub.com/forums/weber-kettles-accessories/how-much-would-you-pay-for-a-yellow/ Good luck.