In the past, it's only taken them a day to prep my order and ship it out. Recently, my last two orders are taking much longer than that. I actually had to e-mail them regarding the first order which was reaching the week mark and still hadn't shipped. Granted, I'm also placing much bigger orders now.
For example, my latest order has 14 items, and 11 of them were already picked and scanned within a day. My feeling is that not everything they have in in stock/storage so they may re-order those particular items and you're stuck waiting for it to arrive.