Many of us that were getting into WFP used supermarket brushes. The Bently brush was much favoured, the only alternative at the time was the Vycan brush made for cleaning trucks, these were heavy too.
WFP window cleaning has moved on since then, and most of us have too.
I used the Harris pole from B&Q for years and still use one today for cleaning glass behind bars. I was the first to adapt the stanley paint pad handles for their brilliant swivels,. now you can buy swivels cheaper from Gardeners.
Don't be put off though, lots of stuff not been invented yet. I have just made prototypes of a simple rectus 21 connector protector, you can pull it around corners and forget about connectors popping off. It beats the hell out of the protector ball.
So carry on mate, without enthusiastic amateurs lots of ideas would never see the light of day.