The Cake Town Patisserie is the cheapest of the three items, at just 15 City Bucks. It is a small, single square item that adds a bonus of 10,000 Happiness Points to your town. For purchasing it, you’ll also receive a bonus of 130 experience points.
Meanwhile, the Zoo is the next item in terms of price, costing 49 City Bucks. It is a much larger item, in terms of size, taking up a 3×3 square area of land, but it also offers substantially more Happiness Points than those smaller items, at a rate of 60,000 points. You’ll also receive more experience points for purchasing it, at 608.
Finally, the Bavarian Castle is the most expensive item, setting you back 59 City Bucks. It is the same size as the Zoo, taking up a 3×3 square area of town, but as a more expensive item, you receive both more experience points and more Happiness Points for purchasing it, at 795 and 64,000 points, respectively.
All three items, as of this writing, are available in quantities of at least 4,700 – head over to the game’s page to add any of them to your town.