Hi Mr. Bill,
I too am a search engine professional, and I want to reiterate what Janeth said: Don't put all your eggs in one basket. There are many
SEO companies out there (ours included), which offer a variety of services. I'd look for one that offers several internet marketing options, and is willing to give you a consultation in advance to determine what would work best for your website/product. Internet marketing is definitely not "one size fits all", and someone who knows the marketplace can steer you away from a bad investment.
Although PPC (pay per click) is a guaranteed traffic provider, it can get very expensive. We always try to combine it with other options to see if we can get the price down a bit. If you can start to achieve solid rankings and traffic on free search engines, it's a much better ROI!
My main caution in terms of looking for someone to help you with internet marketing is to beware of that hype you mention. As in all things, promises that sound too good to be true probably are. We've "inherited" a lot of disillusioned clients from other companies, and it's distressing to me sometimes to hear what promises are made. Check the offer to make sure it's realistic, check the testimonials and case studies they offer, and check the guarantees, to make sure you aren't left empty-handed if things don't work out well.
Good luck!