Depends on how big a hurry you are in, how much money you have, what you can find for sale, and how important upclose macro photos are to you.
There are three models of camera that have great options to adjust for your camera itself and photos that will take great photos - they are the Canon PowerShot, Nikon CoolPix, and FujiFilm FinePix - series. There are many models available for each, so read what you are actually looking at specification wise. For any macro/up-close photos though you will need to buy a macro "lens" for any (later on when you get more money if needed), read below.
You can get a camera local used at a pawn shop, camera shop, or such - but if bought local test the camera and check what it all comes with, and above else make sure it is what you want (don't buy just because it is local waiting a week shipping time can make a huge difference on what you can afford/find).
As you said cheap I imagine you have a small/tiny budget so a even a older DSLR with a macro lens (used costs $500+ easy with the cost of a good lens the bulk of the price) so I would steer you towards a so-called pro consumer or sometimes called "prosumer" camera. It allows you to adjust most of the settings such as aperture, F-stop, ISO, etc, and is much easier on the wallet often around $100+ used.
However in that camera grade, shutter releases (to prevent camera shake), saving to RAW images, and a few other common "must-haves" are usually not available. I have however, have found a way around that with the Canon PowerShot line of cameras using software (memory card installed) called
CHDK. With the software installed, images can be saved to RAW mode and adapting a USB cable by adding
a switch and 3 AAA batteries it can use a shutter release too (and loads more options).
A few things to look for in are a camera are at least 12 MP (high end pro cameras are now in the 50 MP+ area - the image sensor is the real deciding factor but that is way above any quick help guide), comes with a battery and charger (or what kind it needs), that it records to a SD/SDHC memory card (older models will record to obsolete cards), video options (if you want, for example 720p HD), and anything else you want in a camera.
Once you find a camera your interested in be sure to read about it's pro's and con's and any real reviews for it, such as those at Amazon.com (search for your camera model).
Also to get great macro shots, what you will need in the mantid world, a special lens needs to be purchased (like for a DSLR lens $400+ used alone) but as the camera lens is not removable in a pro consumer camera there is still a option. As pointed out to me by user fercho ing, you can buy a
Raynox DCR-250 Super Macro Snap-On Lens for $75 online about everywhere.
Then don't forget some other must haves would be a SDHC 32GB (or larger) memory card (I'd recommend a
SanDisk Extreme for speeds/reliability),
a tripod for clearer shots, camera bag (I recommend
Lowepro or the
Amazon Basic- I've been happy with both), and a good
camera cleaning kit (as used cameras are always dirty, and that is a good starter set), among other things.
For shopping online for a camera I'd recommend these stores as I've had great shipping times/services/prices from them, especially B&H Photo. The links are set to a camera search in the cheap price range..
Another mention is
ebay.com but the problem there is the sellers reliability and knowledge of what they sell, which can often times can be non-existent or worse a lie. Then there is their shipping times/packing, often with higher feedback sellers waiting a week or more to actually ship it (they often purchase a online shipping label and wait thinking they fooled anyone (which is a joke) before they even decide to ship it a week or more later -- the real reason I all but stopped buying from ebay and don't recommend it anymore).. I've had some really great buys but also a few bad ones as well so be careful there.