Besides buying an external hard drive, what's the best way to back up my photos and documents?

I’d like to back up 15GB of photos and 5GB of documents. I have about 10 blank DVD’s…would this be a possibility?

I’d rather not shell out the $100+ for an external hard drive, but I’m wondering if it’s my only option. If so, what type/size do you recommend? Thanks for your answers!