Can i buy/get a server from sandcrawler ?
Not directly no.
You can get one from my friend Jest.
http://main.jestservers.com/ (http://main.jestservers.com/)
Republic Commando and Killing Floor are both $2/slot, if I remember corectly.
You can just use the contact form on his website if tis for a game that isn't in the shop.