Try advertising in forums that could have a potential audience by buying Ads space from the forum owners. If your budget permits you can also advertise about your services in your local town/city in the newspaper or magazines. You can even sponsor events, etc.
I'm also looking for a good place where to start advertising our vmware VPS server rental services.
Our prices, here, an online calculator: serveru-noma.lv/en/server-rental/server-rental-prices
R U looking to sell windows or linux VPS ? And what is the price range? Give us some more information about plans so we can assist you to advertise on the right website.
There are multiple ways of advertising. You can do
Running a PPC program
Classified sites is good way to free advertise for your hosting services