For anything larger than 20", a plasma will generally be much cheaper than an LCD. And in my experience, Panasonic makes the best plasmas (
http://www.plasmatvbuyingguide.com for reviews).
They, and others, make some nice EDTV sets - they're not quite HDTV, but at a significant savings. What you get is a TV that typically will out-perform HDTV with current DVDs, and will only be about 10-15% behind an HDTV when viewing true HD content. The current Panasonic 42" EDTV sells for about $2000, but can be bought without speakers (if using a home theater setup) for about $1700.