Shipping home Souvenirs?

Your mother’s idea will be the cheapest way to get things home.

Mom nailed it!

Yes, but I'm worried about the reference to multiple suitcases. Unless this is a study trip and you need lots of space for things like textbooks, you should try to get by with one not-large checked bag and a carry-on that's nearly empty if you plan to do a lot of shopping. The excess baggage charges will really cut into your spending money, and dealing with a lot of luggage is a drag.

I spent an entire summer in Europe when I was 20, and my suitcase weighed less than 20 lb. on the way to Europe. (That was before wheels, which probably saved 2 lb. or so.) Unlike me, you'll need some cold-weather gear, but don't take multiple bulky sweaters. Plan to layer. Polypro long johns will provide some extra warmth on cold days and weigh very little. You'll probably want waterproof footwear, but resist the urge to take lots of shoes. They are heavy and bulky, and you can only wear one pair at a time.

I would bring a large duffel bag that can easily be stuffed in your luggage on your way there. Fill it during your stay and pay the extra bag fee on your flight home. The only downside to this is you'll have to carry it around until you leave. Also, bring old clothing that you can discard (or donate) before you leave.

Shipping things can be very expensive. The price is set by size and weight, so anything more than can easily be held in one hand is going to cost a few hundred dollars. If you buy something fragile or expensive, often the merchant can ship it for you. Its a good idea as you can offset the VAT with the shipping costs and it will be insured and safely delivered. If you do ship something yourself, the local Post Office will be the cheapest route.

Mail it. There's an opportunity cost built into everything! Hauling stuff around sucks! I've mailed stuff from all over Europe, and never had a problem. It's not that expensive. And just wait until you get home and get to open up all the packages. You could sell tickets to that event.

What we do, if we need to ship stuff home, is mail home the stuff you don't care so much about - dirty clothes, textbooks or whatever and keep your good stuff with you. I was once gifted books at the beginning of a backpacking trip - definitely mailed those ASAP. For that matter, I generally keep any "treasures" in my one carryon, then check a duffel of dirty clothes. The duffel fits compressed into my one carryon until time for the trip home.

For a three week trip, take only one small bag. You will thank yourself each time you change cities! And, my daughter loved shopping for clothes while studying in London, so if you are like-minded, it's even more reason not to overpack.

Short answer -- don't buy crap ("souvenirs") and haul it around to 3 cities.

If you feel you must carry gifts back to family and friends, look for light, unbreakable items -- I like scarves and refrigerator magnets --
preferably from your final destination so they only need to be packed once. Leave the cuckoo clock in the Black Forest! :-)
Review the baggage rules on your airline ticket home so you know how much a checked bag will cost you.