Mason Jar Crafts You Can Make In Under an Hour - Upcycled Mason Jar With Pretty Glass Knob Tops- Quick Mason Jar DIY Projects that Make Cool Home Decor and Awesome DIY Gifts - Best Creative Ideas for Mason Jars with Step By Step Tutorials and Instruction
Centaurea cyanus 'Blue Boy' - Cornflower - can be bought in bunches of 50 stems - cost around max. I could put you in touch with some British flower growers - you may be able to negotiate prices yourself and want to use British grown?
Im really liking this idea with the mason jars. They arent exactly cheap, but are cheaper than most other things. And the blue color is perfect. Pink anemones and ranunculus arent my flower choices, but I really like them.