I found a 10 meter roll of fairy lights, in warm white, from this ebay store, for £9.99 free postage. I thought 10 meters might be too much but it worked out perfectly.
To finish off, get some small squares of fabric, I used green netting and floaty purple stuff for added texture, and place over the top of the vase like how it is on a jam jar. Secure it with some elastic bands round the top. To cover the elastic bands, get some string and wrap around the bands a few times and then double knot it and tie into a bow. I chose string instead of ribbon because I thought it would look more 'earthy' and 'rustic'.
Enjoy your 'Fairy Trap'!