Welcome to the chaos. You’ve been told you need a SIEM. Maybe it was your CISO. Maybe it was your auditor. Maybe your SOC is tired of stitching together logs with duct tape and Python scripts. Doesn’t matter — you’re now on the SIEM buying journey. Congratulations… and condolences.
Let’s walk through how to actually buy your first SIEM without lighting your budget (and your team’s morale) on fire.
Step one: Understand what a SIEM actually does
SIEM stands for Security Information and Event Management. It collects logs from your systems, parses them, normalizes them, and makes them searchable. Then it tries to correlate events and detect bad stuff.
Sounds great in theory. In practice? Half the vendors are selling legacy behemoths built in the early 2000s that now have “cloud” duct-taped to the side. Newsflash, shoving a bunch of outdated tech into the cloud doesn’t make it cloud native. The other half says “AI” every third sentence but can’t parse your custom app logs without a small army of consultants.
Step two: Figure out your real use case
This is the most important part, and where 90% of SIEM buyers go wrong. Ask yourself:
- Do you need compliance (PCI, HIPAA, SOC 2)?
- Are you trying to detect threats across a hybrid environment?
- Do you have a SOC, or is it just you and a coffee addiction?
- Do you need to search some logs or correlate entities and blast radius?
Your use case determines whether you need a log bucket with decent search or a full-blown threat detection platform. If you’re just trying to meet PCI, you don’t need a Ferrari to get to the grocery store. You also want the right tool for your team size.
Step three: Don’t fall for the alert fatigue trap
“Real-time threat detection!” the vendor screams. Sure. What they don’t mention: you’ll get 500 alerts a day for port scans and DNS lookups from internal printers.
You want signal, not noise. Look for built-in detection content that actually works, and ask if you can tune it yourself, without a PhD in Regex. Look for easy GUI-based tuning and rule creation. Even if you aren’t a detection engineer, you should be able to understand what you’re seeing. If you don’t, neither do they.
Pro tip: Ask to see detections for specific threats (like Okta abuse, AWS key theft, or lateral movement). If the vendor blinks, move on.
Step four: Check pricing — and read the fine print
Most SIEMs charge by either GB/day, EPS, or a scan-based system.
Here’s what to do:
- Calculate your current log volume (including cloud services)
- Add a 30% growth buffer
- Look to see if you have use cases for other logs that can actually help, and if you do, add it.
- Get a quote in writing, then double-check the overage fees. Ask if pricing includes storage, search, detection, and integrations, as some vendors treat “basic correlation” like it’s a platinum-tier upsell.
- Ask if data is “hot” or “cold.”
- Ask if you can control retention, partition and ingest.
- Ask what pricing protection controls you can put in place.
Step five: Test with your data, not a sandbox
Demos are great, but they’re polished, curated fantasies. You want the ugly stuff — your Kubernetes logs, your Okta events, your EDR alerts.
Any decent vendor should give you a trial or POC with your real data. Set a 14-30 day window. Validate:
- Can your team write searches?
- Are detections working out of the box?
- Is it usable without training your entire staff?
- Can you easily build dashboards?
- Does this tool cover other areas we can save on, SOAR, Observability, Infra?
If your team hates using it, you’ll end up back here next year doing this all over again. The best thing is to create a score card ahead of time so you’re not swayed by shiny demos. Make sure you have the time to actually use it during the POV, or you just wasted everyone’s time.
Step six: Ask the questions no one wants to answer
Here are a few good ones:
- What happens if I go over my license limit?
- How long does onboarding usually take?
- Can we run this without hiring more staff?
- What happens if we want to leave?
If the answers sound like an evasive politician during a scandal, consider that your red flag.
Step seven: Don’t fall for the hype
What to look out for:
- Major discounts upfront = expensive renewal pricing.
- AI that supposedly fixes everything. Slapping an agent on a badly architected SIEM doesn’t fix the problem.
- Inability to process unstructured data at scale
- If they claim to do everything, they don’t do everything well.
Final thought: Don’t just buy a SIEM — buy a partnership
The best vendors don’t just throw you the keys and vanish. They help you tune alerts, build dashboards, onboard new log sources, and stay sane when compliance comes knocking.
If you’re buying your first SIEM, you want a vendor who feels like an extension of your team, not a black box with a support portal. We seek to be that vendor at Sumo Logic.
