I use a different method for my phone or MiFi internet, I buy a 24 month advance data card for £60, (works out as £2.50 a month) from Three, I don't think I could ever need or could ever use up the equivalent of £25 a month?
I buy my phones for cash and I always buy a 2 x SIM card one, one slot for SIM PAYG telephone calls (I rarely use it, only for emergencies so my £10 tends to last me for 6 months) the other slot for my 24 month SIM card which I tend to use for everything, GPS, maps, shopping, making VOIP telephone calls, booking ahead, downloading books, online banking, Skype ect, etc.
This all works well when I'm hiking. It's always possible to not get a signal of course and when this happens I usually find a way to log onto the internet, via a pub, cafes etc. This year I tried something new, I've bought a small, cheap Doro 2G phone and my PAYG SIM is now in this, the battery lasts so much longer than my smartphone. When on the trail I just use my smartphone as a tablet and just keep it for as long as possible on airplane mode. For me definitely an improvement, I no longer have to keep asking landlords or campsite managers " can I charge my external battery or my phone please" so often as I did before.
I try to work on the principle that I may want everything but I also want it at the lowest price! Why pay a lot when the same thing can be bought for less. I prefer for my hiking money to be spent on, beer, food, and whatever else I need or want to enjoy myself.
My wife likes that about me, I live well on the trail but she doesn't think I'm extravagant.