It’s simple to create a passable time-lapse sequence using an inexpensive digicam and some freeware.
You need an interval timer. I don’t know how many cameras have this feature. However, if you have a Canon PowerShot camera you can download a quite sophisticated bit of freeware called CHDK that, among other capabilities, functions as a user configurable interval timer. CHDK is well documented but the online wiki is a bit intimidating. Don’t worry. Go to this page and work your way down. It gives the essentials.
I used my Canon S95 with CHDK, configured to take photos continuously at five-second intervals. Put the camera on a tripod or other support, use JPEG rather than RAW if this is an option and deactivate your camera’s stabilizer if it has one. Focus manually if you can. Then point the camera at something interesting and start the interval timer. The video below represents about an hour and a quarter in real time, 924 exposures. (Your camera battery will run down pretty quickly doing this, so you may want to turn off the camera’s LCD if possible. The CHDK documentation mentions a way to trick the camera into turning off its LCD by plugging something into the “video out” socket, but I haven’t tried this yet.)
There are probably many ways to stitch the photos into a video sequence. I used Microsoft Windows Live Movie Maker, which is part of Windows Live Essentials, which may have come with your computer if you use Windows 7. (It’s also available as a free download here.) Simple to use: Start a new project, import your photos (batch edit them first if you want), select all of the imported photos, click the Edit tab, set Duration to .03 seconds (the minimum), hit the enter key to apply this duration to all of your photos, then save your movie using the quality setting of your choice.