Few sites I've stumbled across over the years, feel free to send over more to add to the list.
First and foremost, the process of identifying MSRP/Optional Equipment is pretty tedious & difficult depending on the Manufacturer. That being said, optional equip. is probably one of the most important variable's to consider when deciding whether on not to "pay up" for a car. Factory options drive up loan value as well as market demand so do the due diligence & put in the time.
AUDI, VW, FORD, MASERATI, + Others~~If you see a WS attached to a Manheim/Adessa simulcast listing, you can book mark the window sticker and then copy and paste the vin for other window stickers by the same manufacturer. The bookmark will stay live for about a week or so after the vehicle run's through the auction. Then the factory cuts the feed, you'll have to find a fresh window sticker about once a week.
Monromoneylabel.com - I personally believe the $7.00 a report is worth it. Add it as a pack for all vehicles inbound and save yourself the hours, and hours, and hours.....
Chrysler Window Sticker (you'll need to replace the word "chrylser" in the link with "jeep", "fiat", "dodge", ect. As well as replace the VIN number