To buy or not to buy. That is a question that most webmasters and SEO professionals will ask themselves every now and then. On one hand it can be a very effective way to build links. On the other hand is is frowned upon by google and your site might be subjected to an automatic or manual penalty if Google finds out.
I do not recommend that you buy links. At least not unless you are an experience webmaster that can do it in a safe way. It is simply not worth the risk. It is very easy to trigger a penalty if you buy links without understanding how to do it in a way that is unlikely to get you penalized. Never buy links to a website if you are economically dependent on that site.
With that said. Lets look at different types of links that are available to be bought and the risk associated with each type of link.
Paid directories can be worth the price provided that they manually approve all links and that they keep an high standard of inclusion. Google have confirmed that they do not consider this to be bought links and it is not against Google guidelines to submit your site for inclusion in these directories. A good example of a directory that is worth getting listed in is BOTW.
Do not pay to get listed in directories that approve all links. Directories where you are guaranteed a link if you pay the fee. Never submit your site to directory networks where you get a link on a lot of identical directories spread across multiple domains.
Private blog networks
Private blog network are network of websites that are developed for the purpose of selling links on them. They are often built using expired domains.
Most blog networks like this will link to anything and link out to a very high number of different sites. The owners want to make as much money as possible and will prioritize selling a lot of links over the quality of the links. This is especially true for networks that sells cheap links. I recommend that you refrain from buying links on private blog networks. They will often do more harm then good. You might see positive initial effects but the long terms effects will usually be harmful.
There are high quality blog networks but they will charge several hundred a link and will only offer links on individual sites. Not on the entire network. All to make sure that the blogs in the network are real high quality sites and not just spam blogs set up to link from.
If someone offer you links across a network you should always say no. It will end up hurting you more than it helps.
There are a lot of people offer submission services online. These submission services offer to build links from blog commenting, user profiles, forum signatures, guest books, wikisites etc. These services will provide you with low quality links and their long term effects are more likely to be negative then positive. Avoid using all submission services and submission softwares.
Buying individual links is the best and safest way to buy links if you are going to buy links. If you buy individual links you can make sure to only by links on relevant websites. On websites that benefit from linking to you and where the links serve a true purpose. Where your link improve the user experience.
I still do not recommend buying links.