Did you check to see if any of those were either trademarked or had a trademark pending? When I started my company I discovered american3dprinting.com had a cybersquatter who wanted WAY too much to sell me the domain. So I registered american3dprinting.net and applied for a US trademark. It was a long (~6 month) process, but now I have the trademark and that domain the squatter owns is useless to anyone else.