Local currency is Estonian kroon (EEK), 1 EEK = 15.65 EUR.
Euro (€) is also accepted in some places, but they don't have to accept it.
Money can be exchanged in all banks free of charge.
Debit and credit cards are widely used and are accepted almost everywhere. There are lots of ATMs in Estonia.
Tipping is not common in Estonia, but you can always tip for extra good service.
Bargaining is OK at the markets. No bargaining in stores.
As a good comparison article the McDonald's hamburger (the smallest one) costs here 11 kr (€ 0.70).
Normal lunch begins from 40 kr (€ 2.50).
A cup of coffee begins from 10 kr (€ 0.60).
A bottle of mineral water (Evian 0.50 L) costs 10 kr (€ 0.60).
Public transportation. Bus tickets (single journey) vary from 8 - 15 kr (€ 0.50 - € 1.00) depending on the town. One hour and one day tickets can only be purchased by mobile phone in some towns.
In most stores the prices are displayed also in Euros, so it would be easier to compare them.