I get you, I usually mix single flavours at low percentages, comes out very cheap, the nic is the most expensive thing to buy.
I'd need about 20x10ml bottles of manabush a month to say I've comfortable got enough, usually 5ml a day MTL, but it varies so added a few bottles on to that. Easily affordable for some, but not for myself at present. I just have it as an odd treat now and again, usually a multipack or two.
You do make a good point though, I haven't considered using the potv code, so I'll have to relook at the prices, probably have to add £15 every two months for the nic costs too.