I have never gotten nausea or motion sickness from iron supplements, ever. I get constipated from them. And I am not sure where you are from but every Walmart, Kmart, Target, drug store, etc sells supplements, including iron supplements. You will have to try different ones
Depending on how lo your iron is you could try eating differently.
Bran flakes have 100% daily requirement and a bowl of that plus a glass of OJ is a good deal. Along with that, try adding cooked spinach and other greens and cooked beans to your daily diet.