In the end
In the end it really is a case of ‘you get what you pay for’. There are countless occasions where talented bands perform to a crowd on a poor sound system. At the end of the night the audience will generally think they were ok, but nothing special. The same band can play the same songs in the same order, with the same instruments, two weeks later through a professional sound system and suddenly everyone is raving about them.
Members of the public have no real concept of the fact that the only difference was the quality of the sound system and the quality of the engineer mixing them, they just know they liked the second one far better, they sounded like a much better band.
If you care about your show and your reputation, sacrifice a little of your pay just now to hire a good sound company and a reliable engineer. While you may have to pay a little extra it is an expense worth paying: if your show is entertaining and the stage production looks and sounds great, both repeat business and much better paying bookings will mean that the pay will catch up soon enough.
Your music will be properly represented, your band will sound like it should, and you’ll be far more likely to impress people and start your journey to the top end of the live music ladder.