For the price of 3 of these drives, you could buy a 1GB microdrive, even smaller in total "carrying" estate.
I bought one of these drives the other day from Iomega at a similar price. I can't really tell if these 340MB microdrives are the newer generation types (less power consumption, longer battery), or the older models (does anyone know how to differentiate for IOMEGA microdrive? I know you can tell by the serial code on the IBM ones).
If you absolutely need the head room the microdrives can offer, then get one NOW since they are so cheap (I am sure IBM is making headroom for newer models coming out very soon). Otherwise, I recommend a 256MB compact flash card instead; they might cost more ($/MB) than microdrives, but they will also last longer in your portable devices (PDA or camera); of course, if you are using the microdrive in a laptop, then it's not that big of a deal. Finally, the microdrive does feel a bit slower due to it's mechanical "spin-up" time; this may cause some problems when buffering/streaming multimedia files onto your PDA.