With DC1 i used a £4 shawl from Asda and he loved it.
With DC2 i reused that same shawl but she has always hated being swaddled as she likes to wiggle so at 7 weeks she's in a sleeping bag.
Although e were given 2 JJ Cole muslin blankets which would be excellent for swaddling in the summer as they are thin but we use them as a thin cover and comfort blanket, you can get a pack of 2 for £10 in my local TKMaxx.
I splurged on gorgeous Aden&Anais ones and found some bright Faye&Lou ones at TKMaxx for a fraction! Don't actually know yet whether I'll actually be swaddling baybee- but they're great for all sorts of things and have washed really well - super soft!
I'm another or Aden & anais. They are really big, which helped as I swaddled my DD until she was 8.5 months! I bought I'll price on amazon, but have seen them in TKMaxx, if you're not too bothered about the pattern x
Miracle blanket. U can buy at mother care. Basically it's a wrap that makes it so easy, and the babies can not get out of the swaddle so easy. My girl loved it. We would also use Aden and Anais. I love those Muslins. They r by far, the BEST!! However, when she got a month old she could wriggle out and then would wake. She slept better w miracle blanket bc she would stay wrapped. But we use Aden and Anais for so many things! We still use them and our baby is 14 months!