suggest reading up at http://spider-food.net
If they want to hire someone- the owner of that site would be a possible
place to start..
warn the client that there are many sharks/scams in this area..
Some clients of mine have spent lots of money on things that either didn't
work- or worse; actually got their rankings penalized...
any possible they come up with (first- toss out ANY who they found thru
spam)- I'd suggest doing a google.com search on their business name and
domain name, and the same at groups.google.com
the search in groups may turn up possible problems others have ...