The most expensive collection of games I've come across on eBay wasn't LucasArts, it was a $155,000 collection of Infocom games:
https://www.ebay.com/itm/115558782739
I know there have been single games going for more than that, but nothing I've ever had any reason to search for. I don't begrudge them though, because that one probably does belong in a museum. The most ridiculous one, that I don't know if it's still up, was a mere EUR 45. It's the Monkey Island 30 Anniversary Anthology PC Collection Limited Run... Styrofoam Inlay?