Guinea pigs aren't as popular here as they are in the U.S
Its so difficult to find the right things.
I always check pound shops and poundstretchers and things, because sometimes they have great pet things (unintentionally). One I got a 'cat tunnel' in pink, which was lovely and perfect for piggies ..for 1.99!! Similar ones (not as nice!) were at P@H for 9.99!!
And i got a pop up tent perfect for the pigs for 1.00!!