I have a toy website that has been doing very well for the last year however we recevently dropped off the google ranking and I need help in getting links set-up etc. I manage Adwords myself and I have a great web hosting company and I don't want to go to a big company that will charge me a fortune and want to take control of that side of it.
I would be wary. I have worked for a few SEO companies as an SEO content consultant. IMO some of these companies are rip-off artists who are either completely ineffective or charging you a lot of money for work you can do yourself with a bit of background reading. I actually wouldn't really recommend any of the companies I worked for to a small business.
Have you actually dropped off the Google ranking or just gone down a few places? If you have disappeared completely or radically that is cause for real concern and might be an issue with the set-up of your site - ie something might be blocking Google from reading it properly.
If you just want to build your ranking, as I understand it, inbound links from big, relevant sites is your number 1 tool for increasing ranking, and I think this is more a PR/marketing issue than something an SEO company can do for you (most will just buy links in from big blogs - only a short-term solution.)
It isn't all about traffic levels though. If someone visits your website and does not buy, then that's where you need to start your efforts - why didn't they buy, what were they looking for (web analytics will help show you how they found your site, search phrase, ad click, also may show geographic location).