I did this for the Harrowing Masquerade Contest. It was my cheapest costume so far, I mostly used what I had at home. I have to rework it but I'm satisfied with the results considering the time I had.
I think you were the only Cassiopeia costume and I give you "mad props" for that. Unique costumes FTW! This one astounded me, and to say you did it cheaply? bravo! One of my favorites for sure.
It depends on the cosplay. I think around 100€. For this I used all the black fabric I still had at home (as a base for the tail) and got the turquoise fabric for ~2€ or the leather for 5€. Taken as a whole this hasn't cost more than 50€
Yes, I used "Profi Aqua Liquid" in turquoise by the german company Eulenspiegel. It's very easy to use (especially because it's liquid)!
For this I used all the black fabric I still had at home (as a base for the tail) and got the turquoise fabric for ~2€ or the leather for 5€.
Taken as a whole this hasn't cost more than 50€