Quick answer: Jaipur runs about EUR 45 per day mid-range - noticeably less if you eat local and walk. Cheapest window: October-March - warm dry days and cool evenings; avoid the extreme heat of May-June and the July-September monsoon.
What things actually cost
masala chai at a street stall
0.15 EUR
pyaaz kachori snack
0.50 EUR
short auto-rickshaw ride via Uber
1.50 EUR
Amber Fort foreigner entry
6 EUR
dinner for one at a mid-range restaurant
7 EUR
double room in a heritage guesthouse
30 EUR
Eat well for little
Pyaaz kachori at Rawat Mishthan Bhandar - the flaky onion-stuffed pastry Jaipur is known for, about 0.50 EUR
Lassi at Lassiwala on MI Road - thick sweet lassi served in a clay cup, about 0.60 EUR
Laal maas - fiery Rajasthani mutton curry at a mid-range restaurant, about 6-8 EUR
Full vegetarian thali at LMB in Johari Bazaar - a dozen small dishes on one platter, about 5 EUR
Masala chai from a street stall - about 0.15 EUR
Money mistakes to avoid
Visiting Amber Fort at midday - arrive at 8am opening to beat both the heat and the tour buses
Taking the elephant ride up to Amber Fort - animal welfare is poor; walk up in 10 minutes or share a jeep instead
Hopping in rickshaws without agreeing a price - use Uber or Ola for autos and cabs so the fare is fixed
Following a guide or driver into a gem or textile shop - the 'export gem deal' is a classic Jaipur scam
Transport without the tourist tax
The airport is about 12 km from the center; a prepaid taxi or Uber costs 4-6 EUR. In town, Uber and Ola autos are the easiest way around, with most rides 1-3 EUR, and the walled Pink City is best explored on foot.