修改Element UI自带的icon，替换成自己的图片：

定义一个类名，icon使用类名：

.el-icon-类名 {
    background: url('你的图片路径') center center no-repeat;
    background-size: 24px;
}

如：

 .el-icon-date {
      background: url('../../../assets/icon/icon-date.png') center center no-repeat;
      background-size: 16px;
 }

 .el-icon-price {
      background: url('../../../assets/icon/icon-price.png') center center no-repeat;
      background-size: 16px;
 }

 .el-icon-arrow {
      background: url('../../../assets/icon/icon-arrow.png') center center no-repeat;
      background-size: 16px;
 }

<el-form-item class="formSelect" label="建议销售价">
    <el-col :span="11">
        <el-input placeholder="最低价" v-model="searchInfo.minSellPrice"
         suffix-icon="el-icon-arrow">
        </el-input>
    </el-col>
    <el-col class="line" :span="2">-</el-col>
    <el-col :span="11">
        <el-input placeholder="最高价" v-model="searchInfo.maxSellPrice"
          suffix-icon="el-icon-price">
        </el-input>
    </el-col>
</el-form-item>