Be aware those tantalum caps have polarity. If they're installed backwards they'll explode. You'll need to determine which way they were originally installed, but it sounds like dexvx may be able to help or you can try to find a clear picture from other eBay listings or an old review. I have a Diamond V770 but it's not an Ultra, I don't know if it has the same component layout.
Failing that, you'd have to use a multimeter to try to figure out what each pad is connected to.
If you're lucky, you may be able to find replacements on other junk cards or old motherboards. Older cards (ISA-PCI era) tended to use tantalums more often, newer cards basically never have them anymore. I could be mistaken but I don't think there's much of any aging issue with tantalums. They just work until they don't (and they tend to announce their death loud and clear), so I don't think reusing old ones is much of a concern with that type of cap.
My opinion about the seller - yeah it sucks having things shipped this way but I don't think you can really hold it against them since that's (I presume) how it was advertised to be shipped. I didn't see the ad but this is typically how these "gold scrap" lots are presented. If they actually agreed to pad the cards and then failed to do so then that's a legitimate grievance, but if it was an extra request submitted after the purchase, then I don't think you can really consider that binding.
It would have been nice for them to accommodate the request, but the lot was probably already boxed up and ready to ship that way, just barely fitting into the flat rate box that was used. Even ignoring the time, adding padding between the cards would have required a larger (non-flat rate) box which would have changed the shipping expense significantly.
Maybe the shipping rate was inflated (if this was domestic US shipping then I think it was, but I haven't used one of those boxes in a long time). It doesn't really matter though - the total cost is all that matters in the end, regardless of how it's broken down.
