there are a ton of cams out there, what features do you want?
to run through some of the basics:
front only, or front and rear - 2 channel systems generally are more expensive and have lower image quality due to processing 2 channels through one processor, some people choose to run 2 single channel cams instead, but this also means separate power wiring and separate memory cards... everything is a compromise
parking mode - generally you have options of motion detect and time lapse, both benefit from an add on battery, which does raise the cost, some units run separate memory cards for parking mode
form factor - some styles hide better than others, some have screens on them, some can be rotated to film stuff to the side or rear on the fly, some can be moved between vehicles easier than others, etc...
GPS - really only for tracking speed direction and location, might be helpful fighting a ticket if you really were not speeding, some have apps that you can import the data to and overlay on a map, some have it built in, some it is an add on, if its an add on it will cost you a few $$ extra
power supply - you want capacitors not batteries, capacitors are more robust, deal with temps better, have a longer lifespan, more charge cycles, less prone to failure, etc... batteries hold power longer allowing you to use the camera disconnected from the vehicle power supply. for instance if you were going to disconnect the dash cam to bring it out of the car to film the accident you were just in you might get a few minutes of video (or you could use your phone like a normal human), where the capacitor is really just good for a few seconds of power to allow your cam to save the video correctly as it shuts down.
WiFi - generally not needed but can be nice to have, allows you to connect your phone to the camera, common on cams without on-board screens so you can aim it correctly, also allows you to review and save clips to your phone without having to remove the memory card and connect it to your phone or computer
Single Channel in the <$200 range, i would look at:
Street Guardian SC9665GC V3 - $180-200 - great cam, good day and night image, does well in hot / humid environments, company has great support, discrete wedge shape hides better than the more boxy "gopro" style, can handle up to 256GB sd card
Viofo A119/A119S - $90 - 120 - very good cam, good day and night image, the S model is the newer version with improved image and night capability but some are recommending waiting for firmware update (with similar performance the A119 is a better value but with updated firmware the A119S is a better cam), both can handle a 128GB sd card
for a bit more money:
Vicovation Vico-Opia2 - $250 - great cam, very good day and night image, does well in very hot / humid environments, "gopro" box style is not as discrete on the windshield, but allows the cam to be aimed to the side or rear, which may be useful in a road rage or traffic stop scenario, handles a 128GB sd card
Dual Channel options:
another of any of the above
or
Thinkware F770 - full kit runs in the $400 range or you can get just the front cam for $300ish and add the rear for another $100 or so later on - very good cam with good day and night quality, discrete shape looks almost like a toll transponder and hides well, can only use up to 64GB sd card so your record time will be lower especially with 2 cams running, there is an updated F800 model coming soon with a better sensor for better day and night image, not as discrete though and still uses a max of 64GB sd card
Street Guardian SC9663DC - not yet released, pricing unsure (likely $350-400) - similar specs to the SC9665GC, good front and rear image in day and night conditions, same wedge styling, still handles up to 256GB sd cards
there are TONS of videos available online of pretty much every dash cam available
if you are looking at a cam look on youtube for video quality.
make sure you see day and night footage, preferably in multiple conditions (city, freeway, rural, etc) take notice of how the cams do with detail like road signs and license plates, how is the focus for things out of the center of view, at night how do the areas not directly lit look, how does the cam do with moving from sun to shade and back, or high / low light areas at night, or in shade / low light looking to sun / high light, does the image wash out? does the camera adjust quickly? stuff like that...
if you cant find videos from the cam then it is either too new to trust or most likely is shit, there are entire forums dedicated to dash cams, these people geek the fuck out on this stuff, if they are not covering it then it is probably not worth your time or money
related side note:
be careful what sd card you use in a dash cam
and another thing:
a lot of these cams will look similar or exactly like other cams, this is because they are generally all made in the same ChiCom factories. you need to look at the specs and features for the exact model you are interested in, don't be fooled when you see 2 cams that look the same but one costs 1/2 as much. there is a very good reason it is less expensive. sensors, controllers, lenses, etc are often different, if you are unsure check the forums, or ask here and i will... for some reason i actually enjoy researching shit