You can buy travel adapters at various stores, both physical locations and online. Here are some options where you can find travel adapters:

1. Electronics stores: Stores like MediaMarkt, BCC, and Expert often have a selection of travel adapters. You can visit the nearest store or check their website to see the range of products they offer.

2. Travel stores: Stores that specialize in travel essentials and accessories, such as the ANWB shop, often sell travel adapters. Here you can find various models and brands.

3. Online retailers: Popular online stores like Bol.com, Coolblue, Amazon, and Conrad offer a wide range of travel adapters. You can visit these websites, select the desired type of travel adapter, and place an order.

4. Specialty stores: There are also specialty stores that focus on electronic accessories and adapters. These stores usually have an extensive selection of travel adapters. An example is the store ‘Reisstekkers.nl’, which specializes in travel adapters.

When buying a travel adapter, it is helpful to consider the type of plug you need for the specific country or region you are traveling to. Also, check if the travel adapter is suitable for the voltage and frequency of the destination country. Read product descriptions and customer reviews to ensure you choose a suitable and reliable travel adapter.