I have one of these from Alpkit: https://www.alpkit.com/products/hunka

At £30 it's probably as cheap as you will find, I've only used it rarely over the years (and only in good weather) but it does the job for me. I would add that internal condensation is a problem, same as a tent really. However "breathable" the fabric may be there is a limit to what it will cope with and a hot body gently sweating inside a sleeping and bivvy bag does produce some condensation. I simply wait for the sun to come out and quickly dry everything.

For me, on a single night out and travelling light in good conditions it is perfect solution and sleeping under the stars is brilliant experience. Matt.

I there such a thing as a cheap, lightweight, waterproof, breathable bivvy bag...?

I've seen bags that claim to be lightweight, waterproof, and breathable, but cost more than a small car.

I've seen bags that claim to be cheap, lightweight, waterproof, and breathable, but the reviews don't always agree.

Is this like looking for the holy grail...?

Your thoughts would be appreciated.

Peter