Living (aka food) costs in Estonia? Asks a future foreign student

Hello! I hope this post is not too long and tiring to read, but i could really use some advice! Danke.

TL:DR: How much does a sack of potatoes cost in Estonia?

Longer version: I am student from Slovakia, who was just accpeted to Tallinn University of Technology. I do not come from very wealthy family, and so money might be a problem for me. And while Estonia seems similar to Slovakia, regarding prices, wages, etc, i am still not sure about how much money will i need for living.

So far, only way how to find out prices in Estonia was this site: http://www.numbeo.com/cost-of-living/comparison.jsp But i shouldnt rely only on one site.

What does "living" include for me? I should be staying on dormatory, so "place to stay" is settled.

Food is the thing i am not sure about. I would prefer making my own meals, and while i have already asked two Estonians (friend of friend), and found out, that i could get along with up to 30 euros a week, the fact that they still needed like 350euro for living per month startled me. (dormatory and food should fit into 250)

I have heard that clothes are expensive, but i can buy/make these at homeland as well

Prices of cinemas, etc, seem similar to those in Slovakia, and city buses are free of charge, ive heard.

What else is there to worry about?

PS: I dont drink booze very much, so that should save me tons of money

And maybe one more thing: What am i forgetting? I doubt all i need to worry about is price of food, i probably dont even know, what all does "student university life money sinks" include. Any fellow students, who could share their "lifestyles", and whom i could interrogate about prices of stuff?

Thanks a lot!