I have seen many selling websites for new Inventions, from my experiance you need to get out there and make it happen be pro-active in getting your Invention in the Market Place, Is there any one who has actualy sold and new Invention on one of the Invention Auction Sites?
I see the asking pricing and just shake my head, what are they thinking?, the highest upfront payment I will ask for a Clients Invention and that is $60,000- USD and 6% Royalties, do Inventors realise that Manufactures need to Invest lots of money and time in a new product and the Manufacture will in 99% of cases not pay you 1 Million upfront, the best thing to put is by negotiation, not ask for silly amounts of money!
The other thing is there are many new Inventions on those sites that the product is already in the market or something very simular.
From what I have seen 80% of new Invention's should have never got past the Patent and Market reasearch evaluation, I have abandond about 4 Inventions after spending about $200- of each, a good inventor will need to have the skills to also give up on a Invention in the very early stages and not keep going with a poor Invention that will fail. http://www.dereksconcepts.com