I bought an Alpicool C15 model compressor/refrigerant based car refrigerator/freezer for a project. They also have a C20 model which is exactly the same but has a “bump up” in the lid for 20 liters of capacity. I paid $145 with a coupon, and I’ve seen them retail around $190. Here is my Amazon Affiliate link: https://amzn.to/2rwJvD2
Quick summary of the review video above: 15L interior capacity, can get the interior down to at least -12C, chills four 12oz cans to 3.5C in 4.5 hours, freezes 2 lbs of water in 12 hours, draws up to 50 watts continuous when the compressor is running (never goes above 150 watts on startup so can be ran by my Ego Nexus Escape). It averages 13 watts draw over a 24 hour period at 0 deg C without opening the lid (310 watt/hrs in a day). When set to -20 deg C it draws an average of 25.4 watts per hour (610 watt/hrs in a day).
The amount of insulation is relatively minimal (especially if you are using it as a freezer) but the internal volume / total surface area is small enough that it really doesn’t take up that much power as a refrigerator. Its all plastic construction and friction fit lid is cheap (reflecting the price I paid) but serviceable. My unit was damaged in shipping and had some plastic break off the side, but still functioned fine. As I plan on voiding the warranty and most of the exterior case in my project, I didn’t mind, but a normal customer would have shipped it back to Amazon for a replacement.
Video on how to use the control panel (including converting the display to Fahrenheit) is here: