We did little research. We have an interesting results. How much cost some additional services in car rental companies in Prague? 

How much will you pay extra if you need a child seat, winter tires or a second driver? Look at this.

	BUDGET	HERTZ	Avis	Sixt	RUNWELL
GPS Navi	6 EUR	16 EUR	16 EUR	14 EUR	0 EUR
Child Seat	42 EUR	22 EUR	14 EUR	9 EUR	0 EUR
Second driver	42 EUR	44 EUR	7 EUR	7 EUR	0 EUR
Chains	42 EUR	22 EUR	32 EUR	9 EUR	0 EUR
Whinter tires	3,5 EUR	0 EUR	0 EUR	7 EUR	0 EUR
Entry abroad CZ fee	42 EUR	0 EUR	0 EUR	38 EUR	0 EUR
Full Insurance	19 EUR	20 EUR	23 EUR	0 EUR	15 EUR
Unlimited mileage	0 EUR	0 EUR	0 EUR	22 EUR	0 EUR

Draw conclusions yourself.

Prices are for June 2018.