I haven't tried to purchase any boosters yet, but I would be cautious. I saw this post the other day about how one of the biggest booster services turns out to be lining their own pockets with the majority of the money you give them: https://steemit.com/whales/@scarlet7/are-you-paying-randowhale-do-you-know-how-he-is-using-your-money-not-to-upvote-you-with-his-massive-steempower-read-here

The post was downvoted by the owners of the service (with an extremely powerful account) to the point where it was effectively censored. but you can still view it if you click "show." In any case, I wouldn't use that service. I looked into the @minnowbooster service, but it seems like I don't have enough influence on the platform yet to participate.

I recommend using some of the smaller free services like @larryphang (who will resteem your post) rather than paying for a service where it's ambiguous how much of a return on investment you will receive.