What is a ber worth with respect to a vex?

I have a vex and need a ber, what makes the trade a square deal?

I also have the following unique items for trade
Bartucs(2) unid
Templar coat (2)
feral claws
wrist sword
verdungo's (2)
ward bow
fury visor
cerebus bite
blade barrior
heirophant trophy
eaglehorn
marrow walk
eth mancatcher(455)

Think i'll be trading for one or will i be finding one first?

thanks