You would have to get awfully expensive VRM heatsinks then as usually the core block is around ~50 plus another ~10 for VRM's/Paste while full cover blocks tend to start from 100 or slightly upwards and are just for that specific card.
I did not have any decision to make in this regard either, though, none of my cards have a full cover block as they are all non-reference. As I do not swithc my cards all that often I might have gone full cover if given option, do not know. Full cover tends to look better often
If you want build log below post # 10 about half way down. I think I paid 14.00 per 8 there was 24 total on my 2 cards. But it gives good instructions on how to install the universal blocks and the glue to use.