Rackshack is cheap, but, in many ways, you are getting what you pay for. If not less.
eservers.biz have skyhigh setup prices, and rock bottom monthly payments. averaged over a year it is cheaper than RS. I have never used eservers.biz before, so I cant comment on performance.
You basically have two choices economy or performance and service. if you want cheap go with RS or eservers.biz i doubt you will score better than that unless you have your own server to colo somewhere.
If you want performance there are countless other places to check out