Introducing competition during negotiation can provide leverage. Communicate that you are considering other vendors while stating the competitive pricing you've found. This tactic not only emphasizes urgency but also pressures the incumbent to match or reduce their proposed price.
Utilizing the need for compliance and security features, especially if they are offered at no additional cost by competitors, can serve as leverage to negotiate better terms. Point out how your organization requires certain features that are standard in the industry, which weren't originally budgeted.
When there is an increase in the number of users, advocate for economies of scale that should result in lower per-user rates. Point out that expanding your use of Momentum should directly benefit both parties, thus requiring price adjustments in line with this growth.
When faced with a substantial rate increase alongside a reduced scope of services, make it clear that the budget cannot accommodate such increases. Use this as leverage to negotiate a more favorable rate by reinforcing budget limitations and the need for adjustments reflective of current usage.