Hi Yellow Fingers,
You won't find foil containers that are microwave safe. I agrre with Dylan that many places now use plastic containers which are re-useable. In my area we have a Wilkinsons store which sells both the foil containers and the plastic type but I'm not sure of the price. We also have a Poundland store that sells the plastic type at 10 for guess how much? Yeeesss ?1.
Hope this helps,
Cheers,
Blondie