I'll backup TNT with the suggestion of using a DataCenter that rents Dedicated Servers. A server is not cheap (if you want to buy one). In years past I purchased some low end P4 HyperThreads for between $1300-$1600 per machine. By the time you also purchase the extra hardware to have on hand in case something should happen, and then purchase bandwidth, power and have an admin on standby, it's not a cheap venture!
Most servers we purcahsed were through ABMX (http://www.abmx.com
) and Mendex (http://www.mendex.com
) along with some machines through DELL (http://www.dell.com
) and some bare machines through SuperMicro (htp://www.supermicro.com)
If you decide to go the other route and rent a dedicated server you can pay anywhere from $100-$200 per month for a decent dedicated server. The more you spend, the more power you get
You also do not need to worry about extra hardware on hand, or power and bandwidth fees as most providers include between 2,000GB and 8,000GB for those rates. So the only other fee that you'd have is a system admin fee which can run anywhere from $50-$145/hour depending on who you get and what their skill levels are and what kind of oncall status you have them on. If you HIRE the person and keep them on full time, then your rates will be lower (much lower).