看效果： 

代码

<el-form-item label="价格" prop="price">
       <el-input v-model="ruleForm.price" placeholder="请输入......" style="width:350px;margin-right: 10px;" size="small"></el-input>元
</el-form-item>

export default {
      data() {
        var checkAge = (rule, value, callback) => {
          if (!value) {
            return callback(new Error('价格不能为空'));
          }
          var re = /^\d+(?=\.{0,1}\d+$|$)/ ;
          if (!re.test(value)) {
            callback(new Error('请输入数字值'));
          }else{
            value=(value*10/10).toFixed(1)
            this.ruleForm.price=value
          }
          
        };
        return {
           ruleForm: {
                price:"",//价格
            }
        },
        rules: {
            price: [{required: true, message: "价格不能为空", trigger: 'change'},{ validator: checkAge, trigger: 'blur' }],
        }
      }