We've been buying the value marmalade and lemon curd from Morrison's because we've also found that this is a cheaper way to build up a stock of jars.  They cost around 27 pence each so we'll take a look at the mint sauce in Tesco, especially if the jars are slightly smaller because we prefer the smaller jars for chutney.  It's a shame that we have to throw away to contents - but the quality is very poor and if we reuse the jars for years to come then it's not too bad.