I think the supermarkets and food producers themselves have a lot to answer for in creating the perception that something is middle class, because they price it out of the range of someone who is on a strict budget.
I think cumin was mentioned. We use LOADS of that. And loads of other spices and herbs too cos DH and DS are obsessed with curries of all kinds so we make one or two a week. So we go through a LOT of spices. If we have to stick to those crappy teeny tiny Schwartz pots for our spices, that our nearest big supermarkets sell, we'd be skint as they don't last us at all. So I guess then we might perceive them to be "posh". Luckily we have some Chinese and other world food supermarket near us and you can get massive bags of spices and herbs for way less than Tescos etc.
I wonder if demand for tiny jars of Schwartz spices has dropped off as people have cottoned on to much cheaper availability elsewhere, as our Tescos have in the past couple of years started expanding the World Foods aisle, containing much bigger bags of spices, and lentils etc. Half the time when I see people hanging around the Schwartz stuff I want to tell them to go a couple of aisles up and save themselve some money.