Large Influencer shoutout cost for giveaways

I need a bit of help from people with experience with large influencer profiles.

In general, I'm looking for some info on roughly what it would cost (per million followers) to pay large influencers (with 1m, 2m, etc followers) to give a shoutout in the form of 1 post and 1 story promoting a giveaway.

Does anyone have experience with this or can give me rough ballparks?

Obviously there are many variables, but I'm looking to get in the ballpark.

I own an ig agency and if you were just looking at a flat rate it would be about $10,000+ assuming the influencer was legit with a decent engagement rate.

But can i ask is your focus to get more followers/build your brand or do you want more people to register for your giveaways?

I have done this business model, PM ($700+)