I suppose you could pay, but Im pretty sure that the big ones like google do it though crawling through your site. Its all a matter of how the site is built. Having enough content, having correct titles on the page, alt tags for images...there are a bunch of things that go into SEO.

I personally wouldn't trust a company that takes money for that, because there are to guarantees, and I doubt that any business could do better than a designer with the right know-how.

So if you are looking to pay someone for sumbission...I wouldnt know where to point you, sorry.