You have got to use his argument against him.
Ask him to list the Moscow trip cost down to the last £. And that means beer & food money as well as the flight & hotel. Double check his figures so the wool isn't being pulled over you eyes.
Then compare this to the cost of a family holiday for EVERYONE. This doesn't have to be abroad, but if you can afford a break for the same as what he's spending purely on himself then he is being an utterly selfish, spoilt, irresponsible twat if he pushes ahead with this.
At the very least, I find it hard to believe that you could not afford a long family weekend somewhere for what he's spending on football. In fact, I DON'T believe it, full stop.
As for this match "never happening again" ..... well, with someone as determined as this, even if the teams, venue and competition aren't the same next year, there is bound to be something similar crop up which he "has" to go to.
If he insists on going, then he should finance it himself (and none of this bollocks about it being his money 'cos he goes out to work blah di blah). That means selling stuff if it really means that much to him e.g. iPod, PS3, wii, motorbike, car, whatever. He also needs to provide concrete plans for addressing the financial worries you have if he wants to be so selfish. That means that if you are struggling to pay bills, the rest of the family shouldn't have to eat beans, or go without, because he's spent the rainy day fund on indulging himself.
If he can pay for this himself without affecting the rest of you, eg. by raising the money instead of taking it out of the household budget, then fine. If not, then he shouldn't be going. He's an adult FFS and a dad. Whether or not he likes it he has responsibilities.
I'm afraid I have to say that if my partner pressed ahead with this regardless in the circumstances you describe having already been hugely indulged in the past, then it would be a dealbreaker for me. I'm assuming that you've had no similar little jollies yourself ??