I know how the audience not enjoying you can get you down, and I was just starting out! It took a few years (about 20) to get over it, but I will always have happy memories of 700 or so holiday makers joining in when I got up to do my party piece! Also the fun I have had just busking or entertaining mates at a party.
What do I do now? Well, I organise clennell Hall folk Festivalin northumberland! (day job I work in supported housing, where I also run a 'guitar club'!) I gues that in folk it is hard to fill clubs with punters who will pay the fee which represents the actual value of the act. Heck, If I can get to se one or two decent acts a year, at £10 - 20 each + travel + drink 7 food, then I am well pleased!
Also, there are some great semi pro acts on the circut, in northumbria region I can think of loads, all who are regularly on the regional circut, and can be enjoyed for around £5 door enrtance.
As an organiser I baulk at hearing someone ask for £350+ cos I know that the venue would struggle to attract, "can we pull in 50? then that'll be £7 a head!" There are no guarentees, of course, but one act who charged that price v 'a certain % of the door', made just that, and I later heared from a 'representative' that they were a bit disapointed with that! Great act, mind you, but cant aford to hire again! Some of us are disadvantaged by location you know!