Plastic corrugated pipe: 3.97 at Home Depot
Plastic wrap: 4.99 (didn't use much from roll so maybe .02?) (harbor freight)
Black paint: .97 a can for the cheap stuff, I used spray on sealant ($9.97 a can $) to give the skin texture in case anyone wanted to touch it). I used 1 can per tentacle
Plastic bags to shape the ends (free)
That's it! $15.00 a tentacle! You can do it cheaper using just the spray paint. I also plan to add a platform that has a manhole cover with the tentacles coming out of the opening. Maybe a blue or red colored light shining up from below.
There was an awesome tutorial here that someone made using some sort of aluminum tubing for the tentacles. That's where I drew my inspiration from. So thanks!