I wouldn’t be persuaded by discounts and offers - I’m the type of person who sees a voucher code, thinks “ooh I’ll have a look at that” then spends £50 on the site and forgets to add the voucher code at checkout 
I would say that your best bet for making money is to streamline your staff, scale the whole thing back to what it used to be and offer a decent competent site with a working search function, filter by OP, partial quoting etc and leave all the ads in place.
That way it will be a pleasure to use instead of frustrating, and it will benefit ALL users, not just the ones with spare cash. I’m not poor, but I am on a low income, receiving tax credits. I pay for Netflix and Amazon as they benefit the whole family. I could easily afford £50 a year or whatever it is, but I wouldn’t pay it.
One of the main reasons is that I spend a lot of my time on the feminism board. We have been gagged and banned in droves on there for not kowtowing to mouthy activists.
If MN wants to be successful I would suggest standing up alongside JKR and others like her and saying “we stand for women, we won’t be silenced, the emperor has no clothes” and be central to the discussions happening all over the place at the moment. The worst of it has passed - it’s a good time to be vocal, as you’ll no longer be a lone voice. That would show absolute faith and solidarity with your CORE users, and show that the whole “it doesn’t cost anything to just be kind” bollocks has gone too far. Women don’t need to be quiet and be kind, we need to shout and be honest.