I've got a couple of events later in the year where I'll be wearing fitted dresses and need a slip/some shapewear underneath.
One dress is strapless and the other is a narrow halterneck, so I have been looking mainly at the strapless body suits - Skims seem to get great reviews and there are new in box ones on Vinted for around £40 but is it worth it or would an M&S/Next etc version be just as good for less?