Its a cruel irony that the more affordable clowns are native to the most difficult nems to keep. If you must try a nem, start with entamacea quadricolor, but do all your research. They present lots of problems that should be considered in advance. There is also no guarantee occelaris will go in BTA. Mine never have.
While haddoni may be the next "easiest" nem, imo its a world of diffference between a BTA and a haddoni. Haddoni's are very difficult, andpose their own problems in mixed reefs. When buying a nem from the ocean, keep in mind that it could very well have been born around the time of the civil war, and yet almost all (non-BTA) nem die in the first 6 months when in captivity. Don't get me wrong, it can be done, but there is a reason they are labeled as "expert-only" by most stores.