Here are two auctions
each for four 1Mx4 Static Column DRAM Zips.
I very much doubt you'll ever find a DMAC -04, they are like hens teeth. And remember if you did find one you'd have to replace your RAMSEY chip too. They may be dead, but Centsible
was your best chance to get one. They bought all of Paxtron's inventory (who in turn bought all of commodores inventory)
Remember that because you have an integrated scandoubler you can go for a cheaper zorro gfx card. A Cybervision 64/3D, Picasso II+, etc. (Just make sure it is RTG).
Dont forget to visit Amibay