There does not appear to be an option to spend 10 trophies at an Entrance Card (Souvenir Shop) for an Elder Sign in this expansion, unless anyone can advise me otherwise? I have always found this very useful in he base game.

I believe this option was removed from the expansion due to the fact that many found the game to be too easy with that option. But, as I always say, "It is your game, play the way that provides themost fun and challenge for you (just make sure any other players are aware of any house rules before starting)."

Aye, Devon got it right. There is no ES purchase option in Unseen Forces, for two reasons:

a) core game was by far too simple

b) it's rather anti-thematic saving the world collecting items that are for sale at the souvenir shop. Imagine:

"hey, Azathoth is about to destroy the world, and I need 2 ES"

"please, present me 20 points of trophies and these 2 limited edition, save-the-world ES are for you"

"but I have only 8 trophies"

"too bad. we will all perish tonight"

10 trophies for Elder Sign was good offer and I think it should have been left there to be bought, but with little variation. Maybe just 1 Elder Sign can be bought or price doubles for next one and so on. 2nd costs 20 trophies, 3rd 40 trophies etc.

Maybe some dice gambling, like Lost & Found. Elder Sign, monster, doom token, curse etc. being part of the gamble.