It makes me so mad when I put my batter in the liners and part of the liner folds in a bit.
Could it be the more expensive liners hold their shape better?
Where do you buy yours?
it might be that your liners are to big for you pan
Try this: Stuff the stack of liners into a cup or container where they fit snugly, but don't get crushed. This will 'train' the sides of the liner to stand straight up instead of flaring out, which is what causes that collapsing problem. The 'training' will take a day or so, so you may not be able to try it right away. I always keep a hundred or so stuffed in cups and ready to use.
If that doesn't work, see Molly2's reply.