There are a few items to keep in mind when making backlinks:
1. Quality over quantity - It's better to have a few high-quality backlinks than a bunch of low-quality ones.
I did not find a specific offer on the site for backlinks. nor the price, nor the domains that are linked here.
I certainly agree that quality is more important, would you say that all these 812 high DA domains (as you say) from the offer are high-quality backlinks? Any chance to share here which high DA domains are you talking about?