I send postcards and love receiving them too.

Although people may not mention spotting that cards have been posted from back home, I bet they notice. I certainly do and TBH, it devalues the experience. It is worth going the extra mile to find stamps and sometimes it adds to the adventure. Amongst the hardest places I have been to find stamps (i.e. the ones where they are only sold from the single main post office which is never open): Mozambique, Cambodia, Lebanon, Turkey.