Yeah steamdb have a profile calculator
but yeah it only grabs the games current price on steam so misses out whether you grabbed games in bundles and such. Since it can only see what games you have on your profile not when or where you grabbed them and might not have all games if they aren't listed in the store anymore.
Like for me the calculator says with sales it would cost $403us(Lowest possible known price)so its off by $70us at least for me since mines like $326us all up.
-___________- I have error-ed, lol forgot about gift games, quick guess at my gifted games might put them around $50-$70us bit hard thinking about what they might've been when gifted, and then I forgot it doesn't include a few games not listed which look to be around $13us so should've taken that away, and it looks like it doesn't include DLC which would make sense since most doesnt shows up under games which makes it even more whack as more I shouldve taken away. lol my comparison is a failure :\