Had to replace one in a 1.8 2000 Seat Toledo a while back, same platform as the Golf.
Can't remember how much it cost, maybe about the 100-150, this via a dealer?
You could probably fit the MAF yourself in a few minutes, although you may need a secure torx driver.
Seems to be a common enough problem with the VW/Audi/Seat cars from around this time, the performance of the car was quite poor especially first thing in the morning.