I feel for ya. It's not always an easy formula buying and selling Macross. As a collector mostly, I've sold off most of my 1/60's but it was before all the new and revival DX's. Ao demand was a bit better. Also I usually had mine on display so they weren't MISB. So any loss i may have taken was chocked up to having enjoyed the Valk before passing it on.
Also, i never intended to play the buy and re sell game when i was buying any Macross.
As far as buying future DX's , Mandrake is awesome and has great prices.