Things were much cheaper in Holland compared to in Sweden. The food, consumer products and almost everything.
You have to pay 15 euro to get a badge used in LUMC and 15 euro registration fee for the website where you can find houses. A bike is very useful if you don't want to go by foot to everywhere(30 minutes at most to a place in Leiden). A second-hand bike costs at about 50-100 euro and a new bike is more expensive. You can but second-hand bikes on the bike shops on the streets. Just visit more shops to get a bike at a reasonable price.
There are several supermarkets in Leiden, Albert Heijn is the most common grocery store and also the most expensive. I usually go to a medium supermarket near my house called Digros(but no chicken sold there), cheap and good. Other cheaper supermarkets where students like to go in Leiden is Aldo and Lidl, however with less kinds of goods. The supermarket Jumbo outside the train station was also a good choice since it is very convenient with lots of goods and the price was reasonable there.
Since I am a Chinese student, I have to apply for the visa and it costs about 500 euro. That was a huge amount of money.