Right now at Boots, the Summer Infant Swaddle Me swaddling blanket is just £2.99.
I had one of these when my daughter was born a few months ago, and I absolutely loved it. In fact I wrote a review of it here. I found it really indispensable for helping a newborn to settle to sleep. It has adjustable 'wings' so there's no fiddly fussing or having to work out exactly how to swaddle safely, and my baby loved it too.
The product description says this:
"With a simple 3 step swaddling action, the Swaddle Me Cotton from Summer Infant recreates the snugness of the womb, minimising the risk that your baby will startle themselves awake. With adjustable wings, this pink Swaddle Me grows with your baby, while the simple design makes it a doddle for mums and dads to use."
The SwaddleMe is machine washable, and it's suitable for use from birth until baby is around four months, which is when most babies tend to naturally prefer a bit more freedom of movement anyway.
It's not clear why it's this price or what the original price normally is but they're t least £9.99 elsewhere online so I think this is a legit bargain.
The link above takes you to a pink one but there's also a blue one on offer, although that will cost you a penny more. Not sure why!
Standard delivery is £2.95 or free if you spend £45 or more.
With thanks to thefozsays @HUKD.