That’s more the issue, it would have taken me an hour to get there as no transport today and had to have got little fella picked up from school so the overall package if you like became easy to say no.
So the issue isn't really about money, its about the fact that you've been offered a game that is an hour away and it means you'd be struggling for childcare?
If money really is the issue - then a polite decline along the lines of "i'm really sorry but I can't do this game as I have to pick my son up from school and can't arrange alternative childcare" is a good way to go - you don't do the game and you don't come across as a "i'm not doing it for that" type of person.
If you would be happy to do a game for that fee, then something along the lines of "Its going to take me an hour each way to get to the game and I need to be back by <x> time to pick my son up from school. I can help you out if you've got something that is within an <x> mile radius of <insert where you need to be>"
My general advice is that if you do decide to progress up the ladder, sometimes you have to suck it up, especially as you move beyond the local leagues, into supply leagues and beyond. Being in Hampshire, our leagues include the Isle of Wight, which unless you live on the Island means a passenger ferry (20 minutes, relying on the team to pick you up) or the car ferry (1 hour) ride each way. I had a saturday 3pm kick off, I left home at 11am and I got home at just before 8pm - that was 9 hours door to door, for 90 minutes as an AR for a £38 match fee - when you break it down, its not even minimum wage. The week after, for a £40 match fee, I had a game that was less than 10 minutes drive from my house, I left at 1.30 and was home by 5.30.