They're still being made today but in my humble opinion, the vintage ones from the 50's thru the 70's are the best.
When you find the old ones however, they are inevitably missing bulbs--a good source for those is http://www.dogwoodceramics.com/product/ ... lights.htm
They also have the topper stars
Vermont Country Store usually features one ceramic tree vintage inspired repro a year http://www.vermontcountrystore.com
And here's a pix of one of my larger vintage ceramic trees. I hope to post more at some point. This one had been kicked to curb because every single "branch" was chipped but an application of Aileen's Snow-tex hid them all, fresh bulbs from Michael's in this case, and ta-da. The putz house platform in front by http://www.littleglitterhouses.com