Well it seem that you are very new i suggest you create an article about your product at blogger.com and once you have done that,Go and buy the expired domain rather than new domain at
www.godaddy.com and the price is affordable, beside that if you get the rite domain at least sustain more than 2 years,why 2 years? it is because with this domain normally they already have the traffic and backlinks too. so your job will be easier rather than getting the new domain and sometimes with the new domain it difficult for you to get indexes by google and yahoo and there is a lots thing to do.
The process that you have to follow as below:
*Get the right keyword for your product,you can find it here at Amazon.com ,search is there any keyword that suite to your product.
*Optimizing your blog by edit the Meta tag description and keyword(make it short and clear)
*Publish your blog by getting the backlink from the website that has a high ranking more than 5 page rank such Propeller.com,digg.com or shared profit site Hubpages.com by doing this your site will be crawl by the Search Engine and will be index fast
*Rent the web hosting for your domain.
*Inform to Pingabot.com about your blog update this also needed for the search engine to crawl your blog
And if you think this process will make you feel uneasy you can try this without having to do all at the above mention,Find it here to make yourself easy to promote your product:
Understand About Internet Business Here
Try here too perhaps it will help
May be this will help hopefully
Last but not least i wish you luck on the business undertaking.