Newegg has some decent prices on dvi cables(and HDMI cables, and DVI to HDMI cables). If you're ordering the monitor there anyways might as well just throw in a cable too.
And yeah, DVI and HDMI are interchangeable, unless you need the HDMI cable to carry audio over as well. I have a cable that I bought(originally to hook a pc up to my HDTV, but never got around to it) that I've used for a few different things. Including hooking up my PS3(HDMI) to my computer monitor(DVI). Definitely a good cable to have on hand if you have any HDMI devices and any DVI devices. Will come in handy.