Quote Dave Gate:
I think that I should add the caveat that I'm speaking as someone who worked in a purpose-built venue with two rooms holding 1500 and 400 people respectively
For the O/P, if you do reckon you can get 250 punters in a venue, you should be looking to hire a venue yourself and promote yourself. Venue hire....£500 approx. 250 x £7 tickets = £1750 = £1200 profit (less promo costs) plus merch on top of that.