Michael,
What have you been doing to them!
My Form 2s are at least 10 years old, get used regularly and the foam is still immaculate. I do wash the pads fairly frequently and dry them fully which might help.
If you like the sound of the Form 2s, and I assume you do, then 15$ seems not unreasonable to continue to enjoy them. Not sure you could buy better phones for that!
Cleve