One of the latent myths of SEO is the need for a dedicated IP address. This search engine optimization falsehood was started in the late 1990’s and spread by many highly visible SEO’s including Bruce Clay’s inaccurate information.
There is absolutely no need to get a dedicated IP address or a dedicated server for web hosting. You would share a C block IP with your neighbors in a datacenter, and you have absolutely no control of virtual neighbors. If search engines penalized or promoted websites based on their IP address, then IP’s would be more valuable than domain names and blackhat spammers would have a field day holding innocent webmasters hostage.
Imagine this scenario, you are randomly assigned 184.108.40.206 and a site in the same web hosting rack is assigned IP 220.127.116.11 and they are hosting hardcore pornography on a different server. Your website content may be rainbows and unicorns, but the neighboring C Class server could be hosting P2P warez and hate speech. Should Google or any other search engine make an association
Read Matt Cutts dispel the need for a dedicated IP address.
More of the science behind IP addresses:
The four numbers in an IP address are called octets, because they each have eight positions when viewed in binary form. If you add all the positions together, you get 32, which is why IP addresses are considered 32-bit numbers. Since each of the eight positions can have two different states (1 or 0) the total number of possible combinations per octet is 28 or 256. So each octet can contain any value between 0 and 255. Combine the four octets and you get 232 or a possible 4,294,967,296 unique values!
Out of the almost 4.3 billion possible combinations, certain values are restricted from use as typical IP addresses. For example, the IP address 0.0.0.0 is reserved for the default network and the address 255.255.255.255 is used for broadcasts.
Rest assured, you do not need a unique IP address to rank well in search engines. Anyone who tells you otherwise is misinformed or wants profit from selling you expensive dedicated web hosting.