I've installed a few lower end systems before. From my experience, most of them in that price range are basically identical. I am almost positive some of them are probably the manufacturer marketed under different labels.
One thing you need to consider is what exactly do you want to try and capture. With the cheaper systems, the effective range of the cameras is maybe about 10-15 feet, even less at night. Even though you'll be able to see movement and people at much greater distance, but won't make out any recognizable features so it really isn't going to help much.
The most important thing I would recommend is make sure you look at the RECORDING resolution of the DVR, NOT the camera resolution or live view resolution. Most of the systems in that price range will view at 720x480 (called 4CIF), but will only record at a quarter of that resolution to cut down on the processing. It's tricky because you really have to look for those specs. There are some that will record a full 4CIF, but they're not as common. And don't get caught up too much on the marketing of the camera resolution, anything more than 420-480 TV lines is going to outperform the DVR you're recording on.
Even though you said you only need one camera, I recommend getting at least the 4 camera systems. Each camera has a very limited field of view and range, so unless you only plan on monitoring one single item at close range it's not going to work very well. Even a small patio will require multiple cameras to cover it.
Also, motion detection is great, but not essential. For multiple camera systems it saves hard drive space and makes it a lot easier to search through specific events, but all the systems I've seen automatically overwrite old footage, so space really isn't an issue.