USPS online or United States Postal Office has been my favorite online store for quite sometime. I was in POSTCROSSING lately and I am buying stamps online for my outgoing postcards. USPS is a very informative site. You can check how much are the prizes of mailing or shipping different items depending on their weight and size. Aside from those, they are also selling different items like cards, stamps and even Self-inking Stamps, personalized envelopes, and more! I just stopped postcrossing now so it’s been a while since I ordered in USPS store.