A super cheap version, at least for fish:
1. Put fish fillet in ziploc bag, close bag most of the way.
2. Put bag, opening up, in cold water... the water presses the remaining air out of the bag.
3. Seal bag.
4. Put bag in pot or sink of hot tap water, with saucer or bowl on top to keep it under water.
5. Turn (and replace hot water, if you like) after 4 or 5 minutes.
6. Leave in water until fish is more or less opaque (will vary with thickness of fish).
7. Juiciest tenderest fish ever.
Plus, you can do it in a hotel room!