this is quite expensive element and it best to check your possibilities in terms of prices of suppliers, you could find eg. bismuth nitrate, bismuth acetate;
Hello Meignana, I do not know the nature of your research, but there are many salts (organic and inorganic) of bismuth. Apart from the bismuth nitrate and acetate that Ewa mentioned, there are bismuth subsalicylate, bismuth subgallate, bismuth subcitrate potassium, bismuth sulfate, bismuth sulfite, bismuth tritartrate, bismuth phosphate, bismuth trichloride, bismuth borate, bismuth chromate and bismuth citrate. Your choice depends on your research, the solvents (solubility profile) and of course the cost.