On a budget, skip Berlin WelcomeCard — the spend outweighs the payoff.
~€25 (48h) up to multi-day zones
This is logistics, not an experience — its only 'taste' verdict is whether the maths works for your trip. It earns its place if you're hub-hopping across zones (the ABC version reaches Potsdam and both airports) and paying into several sights; the all-in transit-and-faff-removal genuinely saves money and decision fatigue. But the discounts are partial, not free entry, so a central, walk-everywhere trip almost always comes out cheaper buying single AB tickets and museum entries à la carte. The honest read: most first-timers staying in Mitte don't need it; cross-city sightseers on a packed itinerary do.