Why does the price point have to be "around £15 to £20 max"?
If anything the sport, especially the Premiership, has held prices too low over many years now. All subsidised by TV money instead of putting TV money to better use to promote and grow the sport.
The Premiership right now is a £30 product minimum. Some of the best riders in the world going at it. Price it appropriately as the quality product that it is.
Championship at £20+ could move towards £25. What can you get for £15 nowadays in live sport?
British Speedway features some of the best speedway riders in the world, even the Championship is stacked with high quality international riders. Price it with enough margin to go out and sell the product properly. Dropping the price is a lazy way to get a crowd and doesn't work.