Is the 4 licenses all you would expect to need, or is the 4 licenses supposed to be for testing purposes and you would buy more if you decide to use it? If it's the latter, contact them as @bpavlov mentioned. They may/should be able to get you a time limited trial version to test with, which is free, but will expire in about 30 days or so.
If you really only need 4 licenses, I would really look at something else for your management needs. As mentioned, there is no getting around the JumpStart cost for this, even if just for 4-5 licenses. You really won't be getting your money's worth in that case. Jamf Pro is really intended for larger installations.
