I don't see what was so terrible with the setup that you mentioned for a bar doing Karaoke. Especially on a Monday. Maybe that DJ has better equipment but decided to use just that for this bar and it is on a Monday night. How much do you really need to impress the people doing karaoke. People are there just looking to sing, have a drink or 2 and have a good laugh. As a lot of people like myself can't sing a lick.
I mean it's not like it's a DJ doing a party in a bar. When i play inside of this one bar in Orange, NJ here is what i bring. The 2 Yamaha DSR powered tops. 15"'s of course. The Denon 6000, my laptop and external HD. That's it. No sub at all. The bar is a small place and you really don't need a sub. I brought both subs in there once before when i played just to see what they would sound like and they kicked butt. I never had to bring them again because the crowd is impressed and like the sound from just the tops. They sit on the floor and they rock.
Now just remember this. You did say it was a Monday night and this KJ is getting $50.00 for the night more then likely. What would you charge if that were you doing it Canute? Keep in mind this is a Monday night and how much do you think a bar owner is willing to pay a KJ for a Monday night? In my eyes not a whole lot. Lastly how many people would you expect you could get to come to this bar on a Monday if that were you doing it?
Mix, I do not do $50.00 Gigs. I also would not be caught dead using crappy gear for crappy money. I have come too far in this business to stoop so low (This is the way I see it). Being seen like that won't do any good to my image and will hurt chances for future Gigs.
The least that I will charge on a Mon - Thursday night for Karaoke is $200.00 plus free drinks and that is without my scoops, just a single 15" JBL Sub and no Console either. They will also need to have their own screen that I can use for the Singers/audience. It will also have to be in a 5 mile radius of my home.