You can buy the blood IV bags usually at dollar type stores, party supply stores and Spencer's/Spirit stores.
Sometimes they have candy liquid in them but they have the blood bag look.
I made one with tubing and the plastic that comes with my food sealer. I took an image of a blood bag label off of google images, altered it in Powerpoint then printed it on cardstock. I made one slightly smaller bag and filled it with red coloured liquid and sealed it. Then to make the slightly larger bag, I attached tubing to the top and inserted the smaller bag inside with the label in between and sealed it all up.
It looked really good. I had one of those inexpensive pole plant hangers that stick in the ground to hold flowering baskets and suspended the bags from the hooks on them. I just painted the pole with silver paint and made a stand from a plywood chunk and mounted small casters.