Basically it's the national series and if you can't afford the running costs then you should stick to regional or even club racing.
Personally I ran every round of the series and I thought it was the cheapest year on tyres by far, I only used a couple of sets of tyres at RHR and the other astro tracks. The most expensive national was Oswestry and I only used two sets of tyres for each class.
Surely you wouldn't travel up and down the country to race a two day meeting and not put a set of new tyres on at the start of the day?. That in itself means if you run 2 and 4wd you are going to use 12 complete sets for the series at best !!!!!
As I said, it's not expensive for a national series, it's as expensive or cheap as you allow it.
On top of this, every yellow or green minispike that I used in a national heat I used again at regionals/club meets afterwards so that makes it even cheaper
