Well, I suppose the first thing to say is avoid anything that looks even remotely "Asian" and mass-produced. China makes everything nowadays, even "meerschaum pipes", but we can only guess, what material are they actually using (pressed meerschaum, if you are lucky).
I'd personally go with AKB Meerschaum. They are an established brand from Turkey (the primary source of meerschaum nowadays), they use block meerschaum, and their range has both classical shapes and the elaborate carvings. For starters one of their cheaper offerings seems to be the optimum variant. They can be found at SmokingPipes.com, for example.
You may also try Strambach, an Austrian company. As far as I understand, they use not the naturally mined "block meerschaum", but their proprietary "cultured meerschaum", i.e. artificially grown meerschaum (or maybe it's just pressed meerschaum with European standards of manufacturing and quality control, who knows...).
Other variant for cheap meerschaum is finding an estate on Ebay, but it's always a gamble.