You can get decent hosting and a big enough package for a couple small to medium affiliate sites for 10 or even less. Take a look at
ThinkHost, one of our clients. They offer 100 gigabytes server space and 1000 gigabytes bandwidth and unlimited domains for 7.95 a month (if you sign up for a pre-pay plan.)
You can even get bigger plans for less than that but then you need to be careful for all the over-sellers.