I don't know what the most expensive brand new Amiga game ever is but this has to be one of the most expensive second hand Amiga games I've ever seen:
Some poeple are totally crazy on eBay. Either that or they're all loaded to their eyeballs. Funny thing is that I bought this exact same game (in mint condition) from my local car boot sale for 50p!!
If I pick another one up for 50p I'll sell it.