Yeah to be honest it isn't lazyness, more lack of skill.
Painting and modelling is pretty much where I always fall down; fluff and gaming are my strengths.
I've taught myself (and used a few basic guides) to become a high beginner / low moderately skilled painter if that makes sense. In otherwords I'd be advanced for the rank of beginner (I can paint well and smoothly, blend paints, use inks etc), but I lack any of the more difficult skills; and I've never even seen green stuff in real life lol!
Basically I know that if I have to do anything that will take too much skill I'll be less likely to pull it off successfully AND I can't really afford to b*lls up a £20+ model lol.
In saying that, I'm enjoying the idea of using Pre-Heresy Death Guard Colour scheme, so the armour look is probably the one I'll use out of the box.
I like the idea of just doing a large round belly using greenstuff so I might purchased some and have a go.
I was thinking about going for a scyth but that's just so ... obvious. So I might just stick with the sword and have it look like it was dipped in the belly of Nurgle, so it is covered in slime (I suppose greenstuff would help with that?).
Finally I know that the hand (left I think) of the Prince looks kind of like he has his palm semi open, so I'm thinking he could maybe be holding something, although I'm not sure what, as skulls are a little Khornish for my liking.
Thanks for the advice so far guys, any more comments and ideas would be appreciated though.