Does anyone know where you can get the best price on the GO engines?

I am looking at maybe the 25 6 port or the 21 5 port and a pipe. I noticed on Ebay there was a combo package available. Was that a one time promotional deal? Do they even still do that, I haven't noticed it on any of the reputable sites? There is no model number given for the pipe either, but it looks to be packaged from GO.

Thanks!