Well, you need to understand - do you really need OWN ip's? Does it worth money you spend on it?
The thing is, that there are two types of so-called "own" ip-addresses.
First, it is so-called "provider-independent" IP-addresses. Those addresses are also called "last-resort" addresses. Made specially for those who wish to pay for... for almost nothing. "Last resort" means that those addresses may not be globally routable (accessible). If you come to one or more ISPs with those addresses - you may not be able to access some parts of the global network, and vice versa! And your ISP would not be able to help.
Second type of "own" addresses are ISP-dependent addresses. Those are for ISP's only. Your BT ISP has BT-dependent addresses and they at BT need to made very special configurations with thier backbone providers (or next-level ISPs). This is their job as ISP.
If you are going to open ISP company called "XYZ" - you would definately need to purchase some ip-addresses being depended on your "XYZ ISP". Those things and configs can be maintained by ISP only, not by end-customers.
now the question: If you are not ISP yourself, why exactly do you wish to spend money to own IP's... What advantage ?
