Consider this. Forge World Mk.V Heresy Armour Marines (resin) x5 = 23 UKP.
Assuming an exchange rate of 1AUD to 0.65 UKP, this works out as 35.38 AUD for 5 marines.
1 box of Space Marines direct from Games Workshop is currently priced at 62 AUD. That's 5 marines for 31 AUD.
Compare also a box of "combat squad" space marines, cost = 41 AUD for 5 marines.
So, we're now in an interesting era where Forge World resin marines cost significantly less than combat squad marines. They're only a few AU dollars shy of a full boxed set of marines (when doubling the squad size to 10). Is it a good time to be purchasing Forge World armies for the Horus Heresy? Yes, I think so! But note, that these Forge World marines don't come with armaments, so its probably not such a good comparison. Moving on...
Let me illustrate something else that folks may find entertaining / depressing / interesting. Consider an assault squad. They cost 55 AUD at retail from Games Workshop Australia. Compare this to a Forge World assault squad of Mk.II or IV or V power armour for 33 UKP. Converting, 33 UKP = 50.77 AUD. That's 5 dollars (ish!) cheaper than Games Workshop's plastic assault squad! That's really quite remarkable!
Finally, I'll add that 5 cataphractii terminators are also valued at 33 UKP. Add in the armaments (12 UKP) and that comes to 45 UKP. A squad of terminators in Australia now retails for 74 AUD. Doing the conversion, 45 UKP = 69.23 AUD. That's once more cheaper by approx 5 dollars! Again, I'm amazed!