donphan are definitely only worth 15$ each right now. if you look at one website you have to compare the prices of all the cards on that website. im finding on ebay pachis at 20$ each and donphans sell 15$ the energies are always 1-2$ each.
On TnT pachis are 22.99$ and the energies im not sure are for sale there but probably a 1$ each.
I'm interested in your Magnezone Prime and I have a Zekrom Full Art I can probably trade. Is there anything on my list I could add in order to make a fair trade?