One way I get sentences for my flash card decks is using
kanjiscripts, a collection of
ruby scripts that play with data from Tatoeba. Check out this search engine for Japanese-English sentence pairs. You search by Japanese character strings. The output is a text file where each line has a sentence in Japanese (kanji), Japanese (kana), and English. You can easily import this data into Anki.
If you're studying a list of single character kanji, you probably want to learn some words that contain those kanji. Feed your kanji list to
kanjiscripts and the output will be a list of sentence pairs oriented around those characters. Import this sentence list into Anki and have fun studying!
Most commonly-used kanji are in many sentences, although some obscure kanji are not. All of the elementary school kanji are used in example sentences with English pairs in the corpus. Some jōyō kanji are missing (as of 2017-11-12): 升屯弔且丙凸尼斥妃弐臼但吟坑沃杉刹劾奔披抹迭枢阜侶侯勅厘咽帥弧怨栃柳衷軌倣俸准剛剖唆悦挫逓恣脊桁桑殉泰畝租翁耗曹堆尉捗堀渓淑郭陪陵舷舶堕塚媛渦滋猶斑棺硝詠詔軸酢嗣毀廉煎禍褐虞酪鼓嫡辣閥雌勲嘱憬蔽摯璃窯謁賠賦鋳儒墾緻衡諧錦錮嚇礁謹謄藍繭藻璽艶韻.