In reply to tinks:
I've used the exped ones a lot with no trouble. A quick google (to check the brand) suggested they do one with compression straps on the side, but, tbh, I've never found it difficult to squash a down jacket/sleeping bag into a small one without - I tend to push it in, roll the end once or twice, kneel on it, open the end enough to let more air out, then roll it properly closed.
I also use the flat, clear Ortleib document wallets for wallet/camera/valuables - they work well too.
Not sure if there are any reasonable cheaper alternatives - the only one I'e tried was a cheap Aldi one, which was too thick and inflexible to be much use. And much tricker to get into.