As a pack £875
Mine as mentioned £390 
I just calculated how many miles you could drive for that "enlightening".
Let's say you pay about £1.60 per gallon.
£390 divided by £1.60 gives almost 244 gallons.
With an astimated consumption of plus minus 60 mpg you could drive more than 14500 (fourteen thousand five hundred!!!) miles
for the price you payed for a few LEDs.
And then we'd better not talk about the official price tag that Honda attached to those LEDs...
Youre a bit out on your calculations. Petrol is £1.60 a litre, not a gallon (4.54609 litres) so its more like 3168 miles. But point taken.
I spent extra on an EX . Took a bit of soul searching but in the end I decided the extra gismos were of some use, and a bit of extra luxury wouldn't go amiss. I'd already committed myself to considerable extra costs by not buying a base model Dacia Sandero.

But for me an illumination pack was not justified. (After all I'm related to a Dark Lord, Lord Voldemort

)
Two other factors tipped the balance. The EX was available for delivery in 2 weeks, ES would have been least 3 months. And used car buyers prefer top of the range models with metallic/pearl paint . I hope to get at least some of the extra cost back when I trade in an EX rather than an ES or a Sandero. I'm not sure that an illumination pack would add much to its trade value. I could be wrong , they pay silly money for any used cars at the moment.