HuskerBoard

I'm no expert but, in my experience, decent road bikes will run in the $600-$1000 range, but they're worth the investment. I personally believe it's also a better investment to get the bike you want with the elements you want vs. buying something standard that you then have to upgrade. I'd also recommend investing into pedals you can clip into, especially if you plan to bike regularly and for long distances.

I agree with Enhance and would add buying from a reputable bike shop that will help you choose a bike that fits you.  Bike shoes that allow you to clip into the pedals is a must along with a good helmet and padded bike shorts. A really good seat to protect your ‘package’ is also very important. 

Make sure you get a nice lock...lots of bullies will try and take your ride when you go to the arcade...and be sure to lock it up at Blockbuster too...you might think you are just going to be inside for a second grabbing a game to rent...but that is all it takes for Blain McRoberts to mess with your bike.

I've been riding a mountain bike my brother got as a Christmas gift when he was 10 in the 1980s for the past 8 years, and it works just fine. And I've never used it as a mountain bike, I use it to ride on the streets/trails in Lincoln & Omaha.

Long story short I don't think you need to buy a nice bike before you decide if you're gonna stick with it.

That said, it's possible my bike is nicer because it was made in the 80s? Maybe a cheap bike now would suck. I'm not sure.

As ladyhawke said, get a good seat.

I have a 30 year old mountain bike and a three year old hybrid. On different days I like to ride one or the other. The new bike is smoother and the gears shift niftier and there's a better power-to-motion transfer, but overall it's not a better ride than the old bike.

Get a bike that fits your body. Your legs and torso and arms all fit on a bike different than mine. Ride a bunch of bikes from bike shops and sporting goods stores and get something you're comfortable sitting on that just feels right. That's the most important thing.

And get a good helmet. I like Bontrager but get something that feels good that you'll wear. Fashion doesn't matter over wearability. A good looking helmet that you don't want to wear is useless. 

I've had two big crashes the last four years. Your helmet is as important as your bike. Be safe.

My real advice is similar to Moiraines.

First, biking is like joining a gym, unless you are using your bike as your daily transportation more than likely you will use it a lot at first and then less...less and less...

Don't waste tons of cash now.  Get one for free, buy one used...Check it out and if you fall in love...upgrade.

I have seen/known so many people that buy an expensive bike, they buy the bike holder thing for their car, they buy a bike holder thing that they can hang their bike on at home, they buy the clothes and so on...and that freaking bike ends up hanging in the garage where a bunch of wolf spiders have turned it into a spider-condo.

I bough an old Trek for 100 bucks off of CL.  Works just fine.  Had the bike shop clean it and then re calibrate the gears.  We're moving to a development in 3 weeks that has some great bike path near.  Both paved and unpaved so I've been thinking it might be time to upgrade.  The old bike works just fine though so maybe you don't need to plunk down a lot of dinero to get the desired results.  

I bought a cheap Mongoose mountain bike at Walmart.  Works fine for my purposes.  Can't seem to get the brakes adjusted just right, though, and I refuse to take it to a guy.

I seem to remember Mongoose being kinda high-end when I was a kid.  Not so much anymore it seems (If they're selling them at Wally World).

Mongoose was HUGE back in the day...