i wondered the same thing. there are quite a few cg shots, but it wasn't that spectacular. probably the filming in new york is quite expensive.
still when it comes to budget, i am amazed how LotR cost only 90 mil per movie. i mean those movies were huge with ,any cg shots, cg characters and mega battlescenes. sure they saved money by filming back to back but all 3 movies cost 300 mil. that's only 50 mil less than sm3.
Maybe WETA is cheaper than ILM?
Nope. When you compare LOTR to Spiderman 3 , there is a major difference in terms of the VFX.
Spiderman 3 featured alot of CG humans visual effects. Look at the scene where Harry and Peter duke it out. Sure it has some live action shots of TObey but the fight is mostly with Tobey and Franco without masks. They're faces are seen. CG humans are incredibly difficult to animate . You can relate easier to a non-human look VFX then a human looking VFX.
That's the difference between LOTR and Spiderman. LOTR featured many ashots of the massive characters in action , you know orcs and horses and the nazgul. It's easier to see realism. Not only that but when the camera goes in for a close up of a orc , it's no CG character there. It's all make up.
With Spiderman the camera goes full towards the CG characters ( Sandman birth , CG TObey , CG Franco , Venom) meaning you need a better detailed animation.
Those things cost money. It's much more difficult to create CG human then a CG orc.
In the end it depends on what kind of VFX you're looking at. Some things are relatively easy and therefore cheaper to make whereas other things are more difficult and therefore EXPENSIVE to make.
Secondly , time plays an important role. What was a big advantage with LOTR is the fact that they worked for a long time in creating these VFX compared to SPiderman's relative short period. In comparison , Return Of The King essentially had 3 years of work done on it ( if you count all the early VFX work done with FOTR and TTT with the culumination in ROTK).
Massive was developed long before FOTR.
With Spiderman 3 they had to start fresh in developing software to create Sandman . They had a shorter schedule to deliver these VFX.
FInally as for whether WETA is cheaper then ILM :
Remember that WETA belongs to Peter Jackson and ILM belongs to Lucas. Of course WETA animators will bust their ass off for Peter Jackson. Do you honestly think that they would show the same love and dedication to another director ?
Same with ILM. The guys at ILM know that Lucas and Spielberg are best of buds and they will give everything for that too.