Today my family and I took a country drive to a flea market at a tiny, old school. I found a pair of pewter, pillar candle holders from Bombay, India for $2. This is the kind of thing you are looking for to create your wabi sabi home. Items such as this, which are made of natural materials and are not new and mass-produced, or are vintage or antique, that have the patina of a bygone era, take time to collect. The wabi sabi home evolves organically. One does not run out to the mall and buy a complete room's worth of things. You must be willing to leave spaces in your home bare until just the right item can be found. Creating space for something new is part of the process.
The danger to be avoided with garage sales is buying worthless stuff just because it is cheap. Stick with the principle of only purchasing those items which you believe to be beautiful and/or know to be useful. If it is new, it should be handmade. And for every item you buy, plan to give two things you own away! That way you are not accumulating clutter, which goes against the wabi sabi aesthetic. Think quality, intrinsic meaning, and things that tell a story. Imperfect beauty is a virtue. Frayed edges, chipped paint or wood, and rusted metal are not only allowed, but desired!
Wabi sabi is a Japanese tradition, and another way of that culture is to rotate your prized possessions seasonally. Think about how you bring out certain decorations for Christmas, and then you pack them back up for the year. You may also bring out special items for Easter, Halloween and other holidays. If you rotate what you have on display in your home, then you won't be tempted to set everything you own out at once, so you can more easily practice the art of restraint. Another advantage is that it's like having new things every few months! You bring them out and think, "Oh, I forgot about this wall hanging (or rug, pottery piece, or basket)," and you have the chance to fall in love with it all over again. Think also of asymetrical design, like you would find things in nature. A couple of budding branches in an old pottery vase placed alone on a fireplace mantle would be so wabi sabi.
When you head out to flea markets and garage sales, it is helpful to make a list of particular items you need, for instance, wicker chairs for you porch. I have found that when I make a wish list, I'm much more likely to find the treasure, and at just the right price! So put on your comfortable shoes and sunglasses, pack a snack and take a reusable bottle of water with you, and let your wabi sabi adventure begin!!