This is one reason why microtransactions are often aggregated by either pre-selling a pseudocurrency or credit or by having the seller essentially extend you credit and capture payment after several microtransactions have gone by. You can see this on iTunes and the App Store; if you buy a song, you are unlikely to get billed for the song immediately. Apple will quietly keep a tab open for a few hours (or days!) and then wrap all purchases into a single transaction, which is much more economic for them.