How much does Server-side Google Tag Manager cost?

Once you start thinking about server-side GTM, one of the raised questions will be about price. The costs basically consist of 2 parts:

Implementation and Maintainance
Hosting price

Let's skip the implementation and dive into the hosting price.

Hosting Price

I assume, you already have traffic to your website and performing marketing, otherwise you don't need the Server GTM. The price - it depends on the amount of traffic.

The key metrics are:

the number of tracked events on your website
the number of events per second (in other words - simultanious visits)

Let's consider a real example:

A website with about 1M events per month, which is roughly 150000 users/month and 0,05-0,75 requests per second.

Google Cloud Platform

Google Cloud Platform prices vary from region to region, in general, the costs will be:

Cloud Run - 40-80$/month for the main server tag. Google recommends a minimum of 2 instances, but to be honest - the recommendation is too cautious for the given example, 1 instance is more than enough, so I would say just 40$.
Networking - 35$/month. By networking I mean an external Load balancer and Cloud Armor. The networking part can be cut out, the only necessary thing it does - a real-time country detection (GEO Headers). This part is mandatory, if you want to activate Google Signals.
We also need a preview-tag instance. This could be around 0-5$ (request-based billing, lower performance - lower price).

In total for a website with about 1M events per month - the cost is about 80$/month. If you don't need Google Signals (or region is hardcoded) - I think the price is about 40$.

Alternative Options

stape.io- Tariff option for up to 2M events costs 50$/month. It support GEO header for all plans, sound like a cheaper option.
Heroku. Yes you can use any other Cloud hostings - Google Server tag is just a Docker image, which can be launched werever you want. The similar instance (512MB, 1CPU) costs around 25$/month (it is called "Standard-1X Dyno").
Digital Ocean: 29$/month for 1 dedicated CPU, 512MB with autoscalling option

Not sure if you need Server Tag? Read about challenges it helps to solve: Challenges in Data Tracking.