I believe Karstady is one of the biggest department stores in Germany. There's nothing particularly special about Karstadt, but it is a very good department store, which means that if you need to buy something, you will most likely be able to find it here. Whether its clothes, candy, groceries, household goods, kitchen/bathroom things, etc etc etc... Karstadt is a good place to go if you are in town, realize you forgot something, and need to replace it.
What to pay: Depends on what you buy
This is a nice little store with a varity of local, home made liquors, schnapps, wines and cooking oils (e.g. olive, chile) oil that you can bottle yourself. Not exactly yourself; you pick the liquid you want, the bottle you want, and the cork you want, and they do it for you. This is a great place for gifts, or just for yourself. The store also offers a selection of pastas, saucses, mustards, etc.
What to buy: Try some of the local peach, pear or apple liquors, or more common things like amaretto, limoncello, or absinthe.
What to pay: 10 - 50 Euros
The English Bookshop is the best source of English language books in Konstanz. All I've seen in any other store is a small, inadequate English book section, while this store has a great selection of current novels, classics, non-fiction, etc. all in English. This is a great place for those of us in Konstanz who don't speak German very well.
What to buy: books!
What to pay: Average book prices
If you're like me and you like gummy Bears, you'll love this little store. They have your garden variety gummy bears, plus a ton of different shapes (some cute, some "adult") and a ton of different flavours. This is a great store for satisfying your sweet tooth, or buying a small gift for a friend who has a sweet tooth of their own.
What to buy: The "erotic" gummies are the ones I always find amusing. This place offers a number of different shapes in that genre...
What to pay: 5 - 20 Euros
Every tuesday and friday morning, there is a farmers' market in St. Stephans Platz, offering a great variety of local produce, flowers, cheeses, meats, and my personal favourite, fresh pasta. If you're in town for more than a couple of days, this is a great place to get some local products.
There is also a farmers' market in Petershausen on saturdays, but I'm not sure exactly where it is.
What to buy: The local meats and cheeses are always good, but my favourite is one stall that sells fresh pasta. Ravioli, tortellini, gnocchi, and a variety of fresh pesto sauces are all delicious, and very affordable.
What to pay: Anywhere from 0 to 50 Euros, depending on what you want.
"Oh Goooooooood what a wonderful wind jacket ... this is perfect for my dog walking sessions in the winter time !!! Ohhhhhhhh I cannot believe it's only 10 Euro ... I have to step in, I have to step in ... "
And she finally stepped in and got the awful flash orange jacket ... my dear grandma :-)
What can I tell you ? Go there and get postcards !
These are the grandma and Felicitas doing that ...