The Horn of Plenty is Empty

In the last 7 months I've played my saxophone live 70 times. It's been enjoyable establishing my name in the area as a decent musician, but payment for each job is between £10 - £80, mostly the lower. Everyone knows that musicians do it for the love right?
And hey, I'm hungry!
In the depths of winter I'm wondering what's the way to turn this success, from networking and promotion, into a decent living.
If I refuse to work for less than £50 the jobs will simply evaporate. Should I carry on working for nothing? Which a tenner is because I pay my own travel and drinks out of it. Or put up my price and lose the work?
The first is my only choice if I want to be playing with fine musicians a couple of times a week, getting much better on my saxophone and being heard by hundreds of people. But there surely has to be a time when my earnings rise to a half decent income? But there's little evidence.
At some stage I have to accept the economics: to reduce supply is to increase price.
If I carry on as I am, playing my heart out for small change in three different bands, a jazz quartet, a soul octet and a guitar/voice and saxophone duo, the result will be I evaporate.
Sketch by China de Burnay, illustrator/artist. Clarissa Vincent playing saxophone at The Bank, Eye, Suffolk. 
As you can see I am evaporating.