Ask HN: How to find current software/cloud spend for prospective customers?

Hi,

I'm an early stage B2B SaaS startup founder in the data analytics space. I'm looking to understand software spend budgets of prospective customers.

Are there any reliable market intelligence data sources out there that can be used to estimate software spend by businesses - how much they spend on infrastructure (e.g: AWS), databases/data warehouses and other cloud services?

My target market is other pre-IPO software companies in US. Would be great to get this broken down by funding stage of the company.

I understand this might widely vary, but rough estimates are still super helpful.

Thanks!