Do you think most of these ICOs have too many personnel for PR?
Why? As I can imagine, there's so much work to do on an ICO... Or do you think that's not really? Would be glad to learn from a pro.
I would usually assamble a team of 4-5 people. You can always personally contact agencies and negotiate. You really don't need a PR company for the task.
If that's not a secret, what exactly should each of those 4-5 do? Like, 1 - Facebook and Twitter, 2 - forums, etc., or various languages, or what? The user I quoted before you says there's not so much work to do, but 4-5 people seem not a too small team.