The Toyos I had on the same car as you had are only £65 each. Didn't find them particularly hard to get hold of either.
How cheap were you expecting to go?
I highlighted the price differential, and maybe the Crossclimate2 is the most extreme example.
I am a fan of all seasons , and personally I wouldn't want to miss the opportunity to fit all seasons rather than new summer tyres.
There is more choice in summer tyres. The Toyo is a decent tyre and even in 16" is cheaper than the top end 15" all seasons. But the 15" Toyo is still £56 a set cheaper than 16" Toyo on the Backcircles site.
If you actually want the bells and whistles of an EX or the style of the 16" wheels ,replacment tyre cost is not a deal breaker. But if Like Hebden you are doubtful , then tyre choices and price could tip the balance.
Its probably best to do more research on other tyre sites before deciding .
If "Hebden" lives near Hebden Bridge West Yorkshire I'd definitely recommend changing to all seasons asap.