I've not got one, but a couple of mates have Anovas; they're great for meat, fish, and eggs - basically you set the target temperature and leave stuff there for a couple of hours and you'll have perfectly cooked proteins, which you can then dear in a hot pan if you want the caramelisation. Depending on what you want to do with them, decent temperature control is important, so it may not be worth trying to homebrew something if you can get one cheap; I think Anovas were about £65 in the sales? AFAIK Ziploc bags work fine as long as you suck (most of) the air out.