Hey mate,

A couple of people I know selling these items:

Voltaic Plasma Wings - 25,000E - Chidelac (Decent price, may even be a little on the cheap side. But then again out of the three this one's the cheapest)
Solar Plasma Wings - 35,000E - Pretty sure I've seen a forum thread somewhere selling it for this price over the past few days. Maybe sold. Can't find it now.
Cosmic Plasma Wings - Speak to Hadesrebellion, he definitely has an unbound pair. (Probably around 35kE, maybe 40.) Reasonable.

Wings of Summer - Sir-Challisr has a pair I think he whispered me a while back that he is thinking to sell. But don't expect these to be cheap. 60-70kE.
Wings of Summer - I have a pair as well. But doubt i'll sell it for anything under 100kE. (Highball)

Wings of Winter - Spirpo - 42kE. (Reasonably priced. I sold mine for 40kE. These are ugly as hell, but unique I guess)
HelloHippo also has a pair for sale I think but he's only online on steam.

Enjoy the wing-hunt!