fiver gigs for temporary social backlinks.

hi,
im soon to be buying a website that needs a bit of SEO done in order to bring it back to its former glory.. i am willing to outsource and pay the £500 a month for a decent SEO company to do its thing, but being an SEO myself once upon a time, i feel its about time to bring myself back to my former glory aswell.

i have been out the game awhile and i have been reading up on the google updates of the last couple of years.. and im aware its all very social targeted at the moment, and will be for, well forever now i guess!

my question is simple.. now i know fiver gigs are 'you get what you pay for'. but is something like 'posting my link to 500k+ facebook fans' worth doing on an SEO basis? this would create a very good temporary social link for google to see, and from what i know, this would be a very good way to boost ranks, if done every so often via different gig vendors.

am i right? is it worth the 10 bucks? id type up a very good targeted post myself, and simply pay them to post to thousands of users.

would this work? or would it cause issues?
does google know whats happening here?

any help on the matter is greatly appreciated.

cheers