Let me make it clear, I am NO wine expert!!! Good at consumption that's about it. But, recently, the ex boss of Waitrose did an article on why not to buy cheap wine, indeed, in UK, not to pay less than £10 per bottle. His reasoning, which I thought to be sound, was that when you consider the cost of transport, the bottle itself, bottling, storage labelling and transport to the eventual shop is circa £3 per bottle, of anything.
So if you buy wine at £3.50 per bottle, the actual wine is worth just 50p If you buy wine at £5 per bottle, you get £2 worth of wine. His level of £10 per bottle was based on his opinion, note not mine!, that any 70cl of wine for less than £7 wasn't worth the bother.
Seemed reasonable to me.
That said, when we go to France, or, Spain, we always buy a few cheap bottles from a supermarket near the ferry port (assuming we're going back on the same ferry) and drink it on the holiday. If good, buy some more on the return trip, if crap, then nothing really lost!!
Mrs H, being of the Yorkshire persuasion, where £5 is a VAST amount of money, however, cannot resist the 1 or 1.5 eurothingy's bottles she sees!! Most have been surprisingly good!