"Get 50 widgets free and $y thereafter" vs "$y, first 50 widgets free"

Is there any evidence that the order of this promotion copy matters?

For example, let's say I want to give away 50 widgets for free and start charging $10/month thereafter. Which copy generally converts better?

Case A

Get 50 widgets FREE

$10 per month thereafter

Case B

$10 per month

First 50 widgets FREE

In Case A, there's an immediate call to satisfy a "what's in it for me?"
In Case B, there's a recency effect.

Obviously, a split test would provide more information, but that requires resources.