Felt like throwing $30 away and tried this out.
Zero on-demand limits (which is less than fresh account limits, by the way); default spot limits; reserved instances are limited to 20 (as by default), but no instance can be purchased.
When I tried to request a spot instance, got the following error: "failed: This account is currently blocked and not recognized as a valid account. Please contact
aws-verification@amazon.com if you have questions."
In other words, useless scam.