I'm not sure how interesting this is going to be but hey here it is anyway.
Tesco are doing a line called 'Greenerliving' microwave food containers. The nice thing about these tubs, is the fact that they incorporate a small one way valve in the lid. Handy for freshly roasted beans unfortunately they're plastic cant have everything I guess.
The tubs in the following image are £1.50 each and they will EDIT! (easily hold a one pound roast ) hold slightly less than a roasted pound. They are type 5 plastic, the rim of the lid is of a soft rubber type material creating a nice seal. You can see the valve in the upside down lid in the foreground.