currently I'm running 12 MNS. Each one has about eight articles on it and I have another 2 in queue for each one.
I did on-page SEO, adding articles regularly etc. So I think it's now time for the off-page SEO.
My question is do you think I should use (SD) services for that or should I buy some tools and do the work myself?

Also I already did some calculation:

Using Services
(price for all-in-one seo services about $30 per site)

12 Sites * $30 = $360

Buying tools

$89 GSA Search Engine Ranker
+$67 Wiki Bomber
+$77 Captcha Sniper
+$0 Creating Facebook, Twitter etc.
+$?? Private Proxies

= $233 + Private Proxies

So I think it would be better to buy my own tools and do the work myself.
Especially because I have to buy the tools just one time and can use them how often I want.
Also I'm going to learn a lot of things and gain experience during the process.

Am I correct or do I have an error in reasoning?