"Look....I do video production/editing. I am not a professional Wedding Videographer. I am only thinking of this a side gig to make extra money. My friend happens to be getting married this weekend and I can use this opportunity to develop a package for them and use in my portfolio."
If you are an editor, you understand the need for good, clean footage. Decent codec and good audio, right? You say you are a groomsman, so someone else is in charge of filming, right? Do they know what they're doing?
"1.) Like I said before...they do not care about having a top of line, overpriced video camera"
They may not, but others will, guaranteed!
"2.) A cheaper Sony true HD camera from Sears...how can the video not look good? Its HD."
No one is saying it can not look "good." But these consumer lines have their limitations...especially with sensitivity, probably the number one most important part of shooting wedding video. All video is handicapped by light, you need it for the shot....the less you spend, typically, the more light you're going to need to get the shot. Also, manual control. White Balance, colors, focus, ND filters, Audio is HUGE!!!! If you're planning to use a consumer grade camcorder, you will need to record your sound separately, eg. Zoom H4n. Audio can ruin your piece. It can also make your production.
"3.) I have a plugins with Final Cut Pro that can give the video a "filmic" look."
LOL. That's funny. So do I. But if you shoot it without that "fimic" look, you're not going to achieve it in post with filters or plug-ins. I promise
"4.) Instead of charging outrageous prices of $1500 or whatever they charge. I would only charge a few hundred dollars."
$1500 is cheap and certainly not outrageous for a decent video shoot. Realize, most folks willing to invest in wedding videography are looking for something decent. If you're editing skills are up to task, and you want to pursue this as a "side" project....do the same with your "shot" skills. I think you'll be amazed at how "not easy" it is to get a shot that "looks good." Seriously. As you know...it took you a while to get the hang of editing and to execute efficiently. Shooting is another skill set entirely. You may want to explore hooking up with someone who has cameras and is into shooting, maybe not so much into editing. Together, you'll make a great team. 50/50 split on the proceeds, or whatever you guys/gals deem fair. OR, rent some gear. Don't underestimate the power of an assistant. AND, backup gear. If it can go wrong, it will.
"5.) My editing skills are not average."
Than you understand what "good footage" is compared to "crap," right? Your codec is what ultimately will matter in post. FCP does not edit AVC natively, you're obviously aware of that as an editor....another step with the bulk of consumer camcorders today....there are other proprietary codecs to take into consideration as well. Frame rates....are you truly looking for that "filmic" or "cinematic" look? May want to explore cams with 24p. Again, not easy in post, best with Shake....but not a "plug in"....Lighting and Audio are important, as you know....being an above average editor. Expect to spend some money on both aspects. Backup gear is mandatory....not matter if you're charging 20 bucks or 20,000. Folks expect a product at the end. If your camera fails you without backup, you've failed the client.
I'm not trying to disuade you from the game. Rather, prepare you. Seems you consider it a simple task. I've been shooting weddings and doing the audio/still production for almost 20 years. It's not easy. It requires a lot of work and planning and money and gear and time. Don't take it lightly. Edit this wedding and see what you think. Keep in mind, weddings can also be VERY boring. It's not like shooting sports or events. Dress nice and act professionally.
I could keep going but I'm sure you get my point. Also, remember to bring backup media (SD, HDD, P2, SxS, mini DV, etc

)
Peace
J