Last year my husband and I created this giant spider. I found a plastic sandbox turtle at the flea market for $5 and I instantly knew what I could do with it. My DH was skeptical but he played along.
We primed the turtle white, then covered it in spray foam for texture. The spray foam was an experiment, but it didn't end up making much of a difference.
Then we spray painted it black.
We screwed 3 pieces of PVC into the bottom using PVC clamps, so the PVC legs would have a place to attach to. At the ends of the PVC there are angled connectors so the legs go up.
I'm missing photos for the next steps but its not hard to imagine. I created legs out of more PVC and connectors, then I covered them in the foam pipe insulation. We poked holes in the eyes to insert lights. The legs were a bit wobbly in the wind so we used gardening stakes in the ground and up into the legs for support, so they didn't topple over. Screwing the clamps tight prevents the pvc from rolling as well. I don't remember how much it cost total but I'd guess between $40-$50 for both the spider and victim.
I created the spider victim by making a 5ft "t" frame out of more pvc. Then I taped a bunch of plastic bags around the frame to make it more human shaped and bulky. Then I wrapped him in the fake snow sheets used in Christmas decorating. Then I wrapped some fake spider webbing around that. We left him outside for about a month and he held up well to the rain.