On my car, fuse 8 covers the power receptacle, so I used that for the dashcam. Since fitting it about 10 months ago I have recorded some astonishingly bad driving, mainly unfortunately by impatient ladies! My one has a 32Gb SD card which can record 4 hours of HD video
I bought it from Gearbest in the USA and it was $43 including the card and shipping. I imported 16 of them to create a group buy and saved on the shipping and insurance