ORIGINAL: WIbuckchaser
I own one Moultrie 4.0 and have had pretty good luck with it. Good quality pics, excellant battery life, and it runs around $199.99.
Lets not "mislead" the guy. The best pics ive ever seen from a D40 are okay at best (very grainy).
For under $150, i would go with a Stealth I590 or I550 (some work great, other suck, its the risk you take)
For mid-level cams you cant beat the I/M-40/60, the Cuddeback Capture flash, or the Scoutguard (personnel fave is the Cuddeback....stay away from the IR model).
For high end cams, go with the Reconyx, a BuckEye cam, Camtrackers or some of the custom cams (IE the bigfoot)
You could also go the home-brew route which im not that familiar with.
Links:
http://www.bfoutdoors.com/complete_trail_cams.html
http://www.cuddeback.com/
http://www.stealthcam.net/
http://www.moultriefeeders.com/catalog.aspx?catid=gamecamera
http://www.buckeyecam.com/main/
http://www.camtrakker.com/
It all comes down to what you want to pay.