If you invest in polybags at all, I would try to stay clear of polybags that are available nation-wide, and are NOT exclusives. Exclusive ones are usually purchaseable via a minimum purchase price, and almost always have a lower production quantity than non-exclusives. I'd look at monthly LEGO Shop at Home free polybags and the occassional TRU polybag. Just keep your eyes open for them, and try to go to the physical LEGO store fairly often, since they sometimes sell old extra polybags for $5 a piece or so, even if the polybag is worth $25+. Hope this helped!