How to price a newsletter sponsorship?

I have launched fullremote.it in January and is gaining some traction. It's a weekly newsletter with a curated list of job posts for italian remote software developers.

Some numbers:

• 714 subscriber (+73 in the last 7 days, so hopefully 750+ by the end of the month)
• ~75% opening rate (sent 7 newsletters already)
• Topmost links are clicked ~40 times

I have already requests to sponsor the newsletter (companies are asking me to insert job posts) and I was wondering how to price those ads.

Here is a newsletter example

I sure have to work on the template, but that's the structure: some words about the company, list of links to ads.

My idea was to ask 99€ for a "block" with max 3 ads and some background color to make it stand out.

A friend of mine was suggesting to charge something like 39.99€ per single ad...

Open to change prices and to more ideas, but what do you think could be the right model? Single ad pricing or block pricing?