If you're a budding portrait photographer, you don't really need to drain your budget on a whole slew of backdrops for your shoots. It's better to choose a highly adaptable colour that can change dramatically depending on your lighting, like grey. In this video from photographer Joe Edelman, he explains how you can use a middle grey (18 per cent) to shoot a wide range of colours, from black to white, and with gels, any colour of the rainbow. A lighter grey would be difficult to get deep colour from and a darker grey, as you'd expect, will never really read as white, no matter how many lights you aim at it.
Once you have your background, whether it be paper, vinyl or just matte wall paint, then you can get to work using your lights to achieve different looks. You can see how Joe adjusts the darkness of the background in a single-light setup by changing the position of the subject and light; closer to the background, and it will be lighter. Farther away, and the grey background drops almost to black. Adding a background light lets you create a gradient and can also blow out the background if you want to go fully white.
Add colour gels to the equation, and you'll see how the grey backdrop reflects a pleasant and rich velvety colour that isn't blown out. As is often the case in portrait photography, a lot of the work comes down to how you light your scene. That's why you really only need grey -- if you put your lights to work.