This is a touchy subject, and it's difficult to discuss it, from a professional's perspective, without sounding condescending and, well, just plain mean. Please know that's nowhere near my intent.
You're looking at charging people money to shoot their wedding, but you're wanting to do it with gear that any true "pro" wouldn't even use as a back-up body. Even a pre-owned body in the price range mentioned is going to be substandard. The fact that you're wondering about this hints at the likelihood that you're nowhere near ready to delve into this area of photography. "Good photos", while largely due to the skill of the photographer, are also impacted by the gear you choose to use. In the time it's going to take you to gain both the requisite knowledge and experience, cameras that are selling for $300.00 to $400.00 now are going to be relegated to pool toys. They'll be virtually worthless in the grand scheme of professional wedding photography.
You're also not going to want just a single camera body. If you agree to shoot someone's wedding, and your camera gives up the ghost (believe me, you don't want to tempt fate), what are you going to do? You need a second body. It's insane to embark on a wedding shoot without it. If your body fails, you could open yourself up to potential legal action. Also, word-of-mouth is a powerful thing, and you can be assured that the words coming out of mouths regarding your wedding-photographer prowess will not be favorable.
I've shot one wedding in my years of shooting, and I have absolutely no intention of ever shooting a second. Yes, there's certainly money to be made, provided you possess the skills, and possess the gear to let you flex those skills. There's a place for budget wedding photography, but it's no less stressful. The people paying you want the absolute best you can provide, providing the results are what they envision. If they're not, you can bet your last nickel that there will be problems.
I know some wildly successful wedding photographers. They're working, literally, all the time. If they're not shooting, they're editing. If they're not editing, they're dropping off jobs at the lab. If they're not doing that, they're doing any of a number of things that need to be done by successful wedding photographers.
And they do it while knowing that a single screw up can sabotage their career...