Publisher gives you development budget because most games arent made by one person and you need money. At least $50,000 - $150,000 for a small PC games.

Then publisher takes 70-90% before recoup and 50% afte of what remain after VAT, refunds and Valve's 30%.

Problem is when you spent $100,000 and sold lets say for $400,000:

* Valve gets $133,000

* Publisher gets $100,000 + $90,000

And you get $90,000 and real number would be much worse because VAT, refunds, etc.

Oh, dont forget to pay your taxes on $90,000. Good luck!