Quick answer: Los Angeles runs about EUR 210 per day mid-range - noticeably less if you eat local and walk. Cheapest window: March-May and September-November - warm, dry and clear; early summer mornings are often overcast ('June Gloom').
What things actually cost
street taco
2 EUR
specialty coffee
5 EUR
15-minute rideshare
18 EUR
Getty Center entry
free, parking 22 EUR
petrol per liter
1.20 EUR
mid-range hotel double per night
180 EUR
Eat well for little
Tacos al pastor from a street truck - the essential LA meal, about 2 EUR per taco
In-N-Out Double-Double with fries - the cult burger, about 6 EUR
Eggslut sandwich at Grand Central Market - about 9 EUR
All-you-can-eat Korean BBQ in Koreatown - about 30 EUR per person
Fish tacos on the Venice or Santa Monica boardwalk - about 12 EUR
Money mistakes to avoid
Planning Santa Monica and Pasadena in the same day - LA distances are huge; group sights by neighborhood instead
Driving at rush hour - avoid the freeways from 7-10am and 4-7pm or a 20-minute hop becomes 90 minutes
Expecting glamour on the Walk of Fame - it is a quick photo stop on a scruffy street, not a half-day activity
Ignoring parking signs - LA curb rules are notoriously confusing and tickets start around 60 EUR
Transport without the tourist tax
From LAX, the FlyAway bus to Union Station costs about 9 EUR and rideshares from the LAX-it lot run 35-50 EUR to most neighborhoods. Realistically you want a rental car (45-60 EUR per day plus parking) or a rideshare budget of 40-60 EUR per day; the Metro E and B lines cover a few useful corridors for about 1.60 EUR a ride.