The most common spearer to be imported is Pseudosquilla ciliata - a great animal for a 20 gal setup. These animals are common in all tropical reef flats except for the eastern Pacific. They are all over Hawaii, the Caribbean, etc. Most importers get them occasionally. They come in all colors, but the yellow - orange ones are distinctive. Ask your suppliers to try to find you a 3 inch yellow stomatopod. It will probably be a P. ciliata. Alternatively, ask for a striped yellow and brown stomatopod. It will be a Lysiosquillina, a large spearer. They aren't much fun in a tank - mostly just sit in their burrow, but they can get very large and the strike is impressive. I had a 32 cm one for 6 years. It just died, so I will probably be trying to replace it.
Roy