Well, I think I'm a helpful person recently came up with a good idea, probably not an original one but anyway.
(and hey, this isn't sponsored either, even better hey?!)
Firstly, the simple, easy (and free) option. If you are visiting your local DIY store and happen to be picking up wallpaper samples, not that I encourage you to pick wallpaper samples just for photo backgrounds, keep them afterwards and use them. It's also worth checking out the sale or discounted items as you may be able to get a whole roll for a bargain price, and it won't matter too much if any of it gets damaged as you will have a lot left over.
I love the different colours you can get, patterns and even textures.
I then picked 4 colours to paint two pieces of the wood, one colour each size, and with the other piece of wood I used some of my chalkboard paint. the paint was simply little tester pots from B&Q which were on a buy one get second half price so again, it was under £5. The chalkboard paint was already in my craft supply box from last year.
I love the fact that it's easy to mix and match the backdrop and the base colours, switching around the 2 pink shades and the 2 blue shades. I'm having a lot of fun experimenting and seeing which ones work and for what.
I know this can be done with card but I liked the idea of being able to repaint if needed and that I don't need to tape them up to anything. They're also so versitile that I can simply tape anything to them or hang anything from them if needed.
Alternatively, if you are a fan of scarves, like I am, put them to good use. They are great to build texture and height. Pieces of fabric also work well for this. You could invest in a few fat quarters of fabric, in different designs, to chop and change the backdrop, this again would cost less than £10.