I am an autobody tech. and I am sitting here going jeez. I looked very carefully and I am not sure if I am seeing cracked bondo or if I am looking at metal that has crcked... But I would take a guess that remove and replace a roof for that car would not be more than 20 hours @ around $40/hr and the paint at cost would be around 150-200 depending on if they prime it correctly and use sealer, parts for replacing is the expensive part... but I do know that a quote of $850 looks about right for that. I am also not surprised that there was a quote for $2,000 but I still think that is high. I wish I could see it better. If that is just cracked bondo, it just needs to ground out, the dent pulled as well as possible and bondo reapplied, if that was my car I would use metal to metal filler to repair the area, it will last longer and is sturdier too. good luck and if I can help anymore let me know.
-G