The five layers of the modern AI SDR stack — what each tool actually does
Before we run the calculator, you need to know what you're actually buying, because vendor marketing pages blur the lines on purpose. The modern AI SDR stack has five distinct layers: the CRM (system of record), the sequencer (multi-channel outbound engine), the dialer (parallel / power dialing on outbound calls), the meeting AI (records, transcribes, summarizes, and coaches on Zoom/Meet calls), and the enrichment layer (turns a domain into a verified contact with title, email, phone, and intent). Some vendors compress two or three of these layers into one product. Others sell a single layer at premium prices. The cost game is figuring out which compression is right for your team size.
**Apollo** is the most aggressive compression — sequencer, dialer, and enrichment in one $149/seat license, with a Salesforce-style data graph built in (https://www.apollo.io/pricing). That's the all-in-one play. **Outreach** and **Salesloft** sit at the enterprise sequencer layer only — they assume you already have Salesforce, you already have a data source like ZoomInfo or Clay, and they want to be the outbound execution layer on top. Outreach lists at roughly $140/seat and Salesloft at ~$145/seat for their main tier (https://www.outreach.io/pricing, https://salesloft.com/pricing). Neither bundles a dialer in the base price — that's another $75/seat add-on.
**Gong** at ~$133/seat (https://www.gong.io/pricing/) is the deal-intelligence layer — it records and analyzes every customer call and turns the transcripts into deal-stage signals, manager coaching dashboards, and forecasting inputs. **Fireflies** at $19/seat (https://fireflies.ai/pricing) plays at the same layer but for teams that just need notes and don't want to pay for the forecasting overlay. If your SDR team isn't on calls, you don't need either. If they are, the gap between $19 and $133 is one of the most important spending decisions in this article.
**Salesforce Sales Cloud Enterprise** at $165/seat (https://www.salesforce.com/sales/pricing/) and **HubSpot Sales Hub Pro** at $100/seat (https://www.hubspot.com/pricing/sales) are the CRMs. Salesforce is the enterprise system of record; HubSpot is the SMB-to-mid-market bundle that combines CRM, marketing automation, and a lightweight sequencer in one license. **Clay** at $800/mo flat (https://www.clay.com/pricing) is the enrichment brain — it doesn't replace a CRM, it pipes enriched, waterfall-verified records into one. **Instantly** ($97/mo HyperGrowth) and **Smartlead** ($94/mo Pro) (https://instantly.ai/pricing, https://www.smartlead.ai/pricing) are the cold-email infrastructure layer — shared accounts that run high-volume outbound across rotating mailboxes, which is a different game than enterprise sequencing.
The reason that layer breakdown matters for the calculator: at small team sizes, you can collapse layers. A solo founder running outbound can use Apollo for sequencer + dialer + data and skip Outreach/Salesloft entirely. At 100 SDRs, you generally can't compress, because the enterprise buyers need Salesforce as the system of record, the SDR managers need Gong for coaching, and the RevOps team needs Clay for enrichment that goes beyond what Apollo's bundled data can do. That's where the totals balloon.