At the health food store there are liquid iron supplements called "Spa Tone" that my OB put me onto. Just mix with a little cordial, juice or whatever you like. They don't cause the constipation (to me at least!) They are exy though - $14 for a fortnight's worth.

Also try ginger - ginger ale, ginger beer, ginger tabs, ginger nuts etc. Hopefully you won' have indigestion!