Legal trade rates are 2:1 or 1:1 when it comes to Crystal:Deuterium.
If you are higher ranked than the person you trade with you will get banned for an illegal trade; however, you can always receive an "illegal" trade when you are the one with fewer points.
So, in this case a more fair trade would be 50,000 for 50,000 or 100,000 for 50,000 [crystal for deuterium].
Regardless you have few points, so maybe a higher ranked player will help you out.