I recommend to hit up RyuLion since with this type of budget the best is to rely on manual, proven link submissions.
I've also recently had a call with the guys from
MeUp
And the platform seems quite neat, you get detailed stats related to any page that you may want to include to get your backlinks from.
Filter by niche and all sorts of other parameters - domain authority, language, price etc.
You can write your contextual post copy or get it written by their team. There's link monitoring system in place.
Competitor link gap - hints at what backlinks do the competitors buy.
If you spend more than 2k / month than you're automatically on a dedicated plan. One of the investors in the project should have an SEO background.
They have adult too - but it needs to be activated inside the platform as a sensitive niche (hidden by default).
Here a preview of how the dashboard looks like:
If anyone bought there - would be glad to hear some first hand account.