How to Make Money Online with proper SEO

I have been to many forums and found that people like to do their own SEO initially and then give up later after they do not find reasonable results. I would suggest that they should keep on trying, until they really feel that their sales is directly dependent on their ranking in the search engines.
I have high respect for all the people who have achieved success using in-house/personal SEO and still are able to maintain there top spot for highly competitive keywords like digital camera software or photo software. The world of SEO has changed rapidly and so have the techniques. Now lets start with main subject that is "Making money online with SEO".
The first well-known fact:

Higher the traffic better the sales
It is a proven fact that among the billions of pages that are searched by search engines only a few make it to the top and these top 30 websites make the most business. Type in digital camera software for instance and you will understand what I mean. Do you remember how many times have you gone beyond the 3-4th page of your search page results? I would expect the same behavior from 99.9% of the Internet surfers as no one has the time to go beyond the top 30 listed pages. I am exaggerating when I say top 30 because mostly the top 10 get 75% of the hits. So if you are not at the top you are losing on a huge chunk of sales, unless you are advertising locally and are limited to a local business.

Google adwords is worth a mention at this point as millions use them and know their importance. The users of google adwords know that they will get listed at the top page (sponsored listing) for the specified keywords. However, they do not estimate the sales that they will make. They can easily do it in a month and then change their bid amount to be paying less in advertising on google. Being listed in the top page does not mean that you will end up with guaranteed sales. You need to have a real good sales page that will make the "buyer" feel the need to buy it. Remember it is all about making him feel that he needs it.

Search engine optimization will propel your page to the top 10 without having to pay for the adwords campaign that is a pay per click campaign and you might end up paying far more than your sales. Having said this if you choose the niche keywords for your campaign and have a good sales copy you are bound to make a lot out of the campaign. Out of thousands who click to your page at least 50 should buy your product.

The million-dollar question
How will you benefit from SEO? How much should you spend?
If you have a good product and at a reasonable price compared to competition and feel that you can garner enough sales once your website receives traffic SEO will benefit you by providing you with exposure for the chosen keywords ( a proper keyword analysis for searches per month for that chosen keyword) will be conducted by the SEO expert. Depending on the competition you have for those keywords the plan will be chalked out by him. Sometimes only on-page SEO may take you to the top however, nowadays SEO has become a popular career with many top websites spending huge amounts on SEO to be listed in the top.

Your expense should depend on how much sale you are bound to make. A proper estimation of this can be drawn after the first month that you are listed in the top 10. Your expense can range from any where between $250-$2500 depending on the competition you face.

Be careful while choosing an SEO firm or person as they can use spammed techniques that can get you banned from search engines.