Looking for inexpensive SEO package for fixed price and ongoing monthly SEO

We havd 4 web-sites and I want them all SEO'd without a lot of input from us. We can change some things, but we do not want to rebuild our web-sites. We want to make the most of what we have already and can cahnage some of the structure.

We want an inexpensive SEO package initially for all the sites and may look at an ongoing campaign.

We have blogs on all our sites and news release pages.

We want links created and built and SEO created for the sites below:

Most important www.posturegroup.co.uk
then www.relaxa.co.uk
then www.safetyviatechnology.co.uk
then www.workstationassessments.co.uk

Please give me a price based on one site, 2 sites, 3 sites and 4 sites and fdor initial SEO and ongoing plan after that.

Rodney Epstein