The thing is, this IS a budget/costs issue for organisations.
It's not the £2,500 membership fee that's the issue, it's also the time staff are spending on submissions and drafting policies for Stonewall approval and, much more significantly, the £100,000 in legal fees that the adherence to Stonewall's demands in their staff policies causes when they then have to defend those unlawful policies in Court. That's the expensive bit, and it's all because Stonewall has demanded that organisations stop following the Equality Act and instead enforce Gender Extremism on its employees instead.
So, yes, any organisation needing to control its budget needs to ditch the huge financial liability that is its Stonewall (anti-)Diversity Scheme membership.