The real question is, can you wait for the iPhone 5? With all these rumors, key word rumors, how do we actually know the iPhone 5 will be released this October? There is a chance it simply wont be released this October, i'm not saying it wont be released this year. The announcement at the apple keynote is not the same as the release.
Do you want to take the chance waiting for an iPhone 5? since its mid summer right now, why not get iPhone 4s which could keep you occupied until late 2012? There's no doubt an unlocked iPhone 5 will cost anywhere between $699 - $899. Waiting for the prices to go down on that will take months. The iPhone 4s is in a solid price as of now, still expensive but not as much since the release.
The iPhone 5 supposedly has an A6 chip processor which will double the speed on the iPhone 4s. Do you really need that much speed? You will need to wait a long 3 months until the community developed apps that take advantage of that.
The iPhone 4s has a perfect Eco system, meaning the community is fully involved and tons of apps. For all new apple devices that get released, only very few will develop on it right away. Devs usually take a few weeks trying to learn new features. There is also not going to be a jailbreak for iPhone 5 any time soon (unless we are lucky). This is going to be all new hardware and software that no one is familiar with.
So all you jail breakers are out of luck.
Only reason i would say wait for the iPhone 5 is, for those who don't care about jailbreaking and just want something to show off. Other than that stick to the iPhone 4s for now. Most will be getting the iPhone 5. But don't take that over an iPhone 4s.
Should you get an iPhone 4s now or wait for the iPhone 5?