At e-rewards, you can redeem for 1,000 HHonors points at a cost of "$25" or for 3,000 HHonors points for "$50". You can buy points from HHonors for $0.0125 each or less. That's $12.50 for 1,000. I don't know where e-rewards gets the impression that the same amount of points is worth "$25".
To be honest, I get several e-rewards emails per week and it takes me almost a year to earn "$50". Most of the emails are only worth a few cents. Every once in a while, I get a survey that's worth a few $$. It will take quite a while to earn enough for a free night, even at HHonors' lowest reward level of 7,500 points.
But, you can also redeem MyPoints points for HHonors points. 1,000 MyPoints Points = 1,000 HHonors Points. I find that the MyPoints points add up a little faster, even if I'm only doing their surveys and their emails. It may be worth joining MyPoints as well if you want to add to those free HHonors points.