I think the idea is to get likes from people who may really be interested in your offer after you "warm them up" with some content on your fb page. General likes from anonymous fb users may not amount to much.

Honestly.. to easy to use social exchanges like Follow Like, they are free..

To be honest no they aren't worth buying bots/fake likes. They are nothing then numbers.
But still if you want are interested in to buy then try this free exchange site (NO AFF.) rather than buying from someone.

They have no value whatsoever in my opinion.
Fb likes have no relation on serp ranking, period.
Only they are good for when they come from real people - real profiles. And this you can't buy. Even if they will do it manually, they will make fake profiles and no will follow these like if they look spammy.
Moreover even the likes from the actual people are not giving as much benefit as if the person would actually share the thing to their wall.
However, when it comes from the real visitors and your friends, they would multiply the likes and actually VISIT your site, by and by.

I really I doubt the value of Facebook Likes in a business because some users are using a few apps or generators. Yet, an article on Forbes.com tells me that "Liking is now one of the primary ways people exert their tastes and preferences online, and it has created an entirely new conversation between consumers and brands." It goes on to say that increasing Facebook likes is now a standard marketing tactic incorporated in most, if not all, integrated marketing campaigns. In other words, the more likes you have = more customer loyalty.

It won't help you in any sense. After Edgerank update on facebook, Page likes doesn't matter alot

You can buy facebook likes from fiverr.com. But it is better to get real liks who are interested in your offer. Make a Facebook ads with your page. You will get real targeted fans by this way.

Don't understand buying likes as you want to market back to all your likes. Doesn't help with SEO