They are now selling extra 1800mah batteries PLUS the wall charger on Ebay
HOWEVER I would not recommend buying from this seller since the product
is coming from China
I would wait for a US seller.

2x 1800mAh Battery Wall Charger for HTC EVO 3D Sprint | eBay

Ooops
maybe I should`ve listed this on Evolution`s accessory page ?

I found a US seller in New Jersey last week. They are selling the wall charger and 2 1800 batteries for just under $13, no shipping cost. I ordered on July 3 and it arrived this afternoon (July 9). I haven't tried the batteries yet, but I have one charging now so I can test it. The batteries look exactly like the extended 1800 battery I bought from HTCPedia.com recently and they are the same size as the original Evo 3D battery so they don't need a new case.

ND8 2X 1800 mAH Battery + Charger For HTC Sprint EVO 3D - eBay (item 160608155777 end time Jul-22-11 03:50:00 PDT)

Like I said, I haven't actually used the batteries yet, but will test them once they've charged in this new charger.

yea those work fine
I have the same exact ones

One of the batteries they sent me tho
made my 3D really hot
and I took it out and thru it away

The other 2 batteries work fine

Be on the lookout for something like that

I have those also. They work great. No complaints so far.