Cheap but legitimate way to do a will?

I am just over a week off giving birth so am contemplating all sorts of stuff right now in anticipation for becoming a parent. My husband and I want to sort out wills - we don't have one at the moment, but we also don't have a great deal of value (we don't own our house etc). Is there a cheap but legitimate way to write one? And would this include things like who would look after our son if we both died? Thanks