Extortionate seems a harsh word. It really depends on disposable income and priorities. When mortgage/rent/commute/family come into it then speedway is well down the list of priorities as should be all 'entertainment'.
However, I'm very fortunate as I bumped Sky and BT sports and now I can now afford an Edinburgh Monarchs season ticket and some additional trips to Glasgow and Berwick. Admittedly I do go on my own (loner) so the cost is not doubled plus kids.
I haven't missed Sky or BT at all so far.
I used to have season tickets for football, rugby (local and 6 nations) but gave them up. Too expensive and not value for money was my reasoning.