"X Digital Media" is not listed in the Nikon L10 manual as being "approved." Only SanDisk, Toshiba and Panasonic SD cards are listed... however that does not mean it will not work if it doesn't show up on the list. My personal favorite is Lexar (which used to supply Nikon with the OEM cards, as well as make the memory cards for Ritz/Wolf Camera).
Top names in SD/MMC cards: Lexar, SanDisk, Panasonic, PNY, Kingston, Viking... (some of these cards are actually made by SanDisk and Lexar).
Check other e-tailers for deals. I see lots of 1 and 2 GB SD cards for $10-20 (perhaps not faster than 40x tho). Try Tiger Direct, New Egg, Buy.com, and Amazon... or use Yahoo! Shopping.
Seriously... go here: http://shopping.yahoo.com/
and type in "SD card" in the search...
If you can find a good deal locally that's best cuz if it doesn't work with your camera, the return it as defective and pick another brand.
SD is not SD. There are incompatibilities. I think they are a bit rare these days... but it more of a problem with high speed cards (and non-speed rated cards are painfully slow).
Good luck.