Yes. Our standard hourly rate for Datadog Pro is $0.03 per host per hour. You can choose to pay for all of your monitored hosts hourly, or commit to a subset of hosts upfront on a monthly or annual plan and pay any additional hosts on an hourly basis, billed at the end of each month. This works out to be much less expensive for extra hosts that may come up for a short period, but a bit more than monthly rates if you pay hourly rates for hosts that are up all the time.
Please contact Sales or your Customer Success Manager to enable this for your account.