Depends on the industry. In my world (B2B SaaS) we are spending $90 - $300 for every new lead generated. Of course, every new lead doesn't become a customer. We have to spend $3000+ for every account added to our free tier!
That's really expensive! That means you are spending $3,000,000 for 1000 free tier users. May I ask how much does your Saas charge paying customers? I would love to know the potential revenue to justify the expense.