When I needed fabric recently, I found the cheapest way to buy it was from buying a single duvet cover set (with pillowcase). I unpicked the seams, then washed and ironed the fabric. One side was floral, the other striped.
The floral side was used to make 3 pairs of teeny curtains for the playhouse.
And I made a small tablecloth. 
That left me with the striped fabric. What to do, what to do? Every time I looked at it a voice in my head shouted 'PYJAMAS'. The fabric is light, perfect for the current warm nights.Today, I took a pair of jim jam bottoms and ironed as flat I could so I could use them as a pattern. I wanted them to be wide of leg and nice and long.
I won't lie. There are mistakes.
Because I am such an idle so-and-so, I don't bother to measure. Had I done, I might have ended up with jim jams that came up higher, instead they are a bit 'low slung'. But that's ok. It was my first attempt and I'm just so pleased that they fitted at all.
The sewing is seriously dodgy in places and I'd hate for anyone else to look at them closely. The elasticated waist is made in the simplest way I could think of.
They will do, they're only for me.
Next time I shall make sure I have more fabric at the top, so they come up higher. And yes, there will be a next time because these were amazingly easy to make. When the girl was home from school, I showed her my pyjama bottoms. She immediately said she wanted some. I had a little bit of fabric left over, so set to work.
I'm describing hers as cropped, because that sounds better than 'a bit too short'. 
I'm both pleased and surprised at just how far the fabric went. From now on, I will always buy single duvet sets when I need fabric. It is so much cheaper than buying it on the roll, and a little goes a long way. Plus, you get an extra pillowcase, which is always handy! Pink 'Isabella' duvet cover set from [Dunelm-Mill]