lcd hdtv is just a monitor with extra inputs, speakers, and a tuner.
you want a monitor with a good contrast, a good maximum brightness, and a low response time (black to white), just like a tv.
you also need to see if the monitor comes with hdmi inputs and if you don't have any, built in speakers. if it doesn't and its still a good deal, you can buy a dvi to hdmi adapter for like 3$. however, then you lose the sound hdmi carries. you can get around that if you have speakers using either your regular stereo red and white, or using an optical audio cable.
finally, if you plan on watching TV on this you'll need a tuner, which i have no idea about prices for or what kind you'd need. hell, you might not actually need this any more with the switch to digital, but i have no clue, don't watch tv.
if you're going to shop for a monitor, just keep your eyes on FW or SD deals. techbargains.com is another good place to look.
here from tech bargains, 24in samsung with hdmi for 165$, free shipping.
http://www.techbargains.com/news_displayItem.cfm/204977
no speakers that i can see though.