There are three problems with what people do when they compare the cost of a VB and an ELCS.
The first is they don't consider the costs of a planned VB include the most costly EMCS and instrumental deliveries. You have to add these costs together and compare to a planned ELCS otherwise your methodology is fundamentally flawed and not a fair comparison. (Incidentally, it is worth pointing out that most medical literature and research is actually pretty worthless as even those doing the research have failed to acknowledge this. More often than not EMCS and ELCS are lumped together in data, creating a very misleading picture where the risks of emergency surgery are down played and the risks of planned surgery are exaggerated. This is not good for women as they are being misinformed about the safety of each).
The second thing they do is assume that all women who request an ELCS would have had a problem free VB. This is very much not the case.
Women who choose to have an ELCS rarely do so without some other medical reason - though this alone my not be enough to merit an ELCS - but in some cases it provides a very strong case. It is a myth that there are thousands of women making the decision based on fitting in a date and without regard to their health and the health of their baby.
Indeed there is an argument that these women attempted a VB a sizeable percentage would end up with an EMCS anyway. There is an argument to say in these cases that an ELCS is cost saving rather than more costly.
Bare in mind for example that there is a disproportionate number of older women who ask for an ELCS. Bare in mind that mental health reasons ARE health reasons but are often dismissed and belittled as not 'proper' health reasons. Bare in mind that many women who ask for an ELCS have previously had a very bad tear, and though technically could have a VB could end up with very nasty injuries that end up having to be repaired - something that is not recorded in national data.
And lastly, as mentioned above, they think the costs of birth end in a delivery suite, which is utter bullshit. The NHS bares the cost of any complication and any resulting mental health related issues.
There have been very few comparisons, which take into account any of these three issues.
NICE did look at this briefly, when they considered the costs of allowing women to request ELCS did a cost analysis based on the cost to the NHS of incontinence alone. Based on this there was an £80 difference. They concluded it was impossible to go through every possible scenario (which may indeed have included complications where an ELCS came out worse) and decided that evidence they saw with regard to one of the most common complications, that that there was no justification whatsoever to reject requests for an ELCS on cost alone as they were cost effective and affordable, especially as they also thought that the financial cost of forcing women to have a VB was also likely to be high in terms of mental health finances.
However they didn't consider whether women who asked for an ELCS were more likely to have complications of some sort because the data really doesn't exist in a force that can be used accurately.