Taking values from other rows matching by date, Sql Server

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declare @t table (STORE_ID int, INDEX_ID int, START_DATE datetime,
              END_DATE datetime, 
              GROSS_SALES_PRICE decimal(10,2),
              NET_SALES_PRICE INT 
             );

insert into @t 
values (3,22,'2014-08-01 00:00:00.000', '2014-09-30 23:59:59.000', 29.99,25),
       (3,22,'2014-10-01 00:00:00.000', '2014-12-31 23:59:59.000', NULL,NULL),
       (3,22,'2015-01-01 00:00:00.000', '2015-09-30 23:59:59.000', 39.99,28),
       (4,22,'2016-01-01 00:00:00.000', '2016-07-31 23:59:59.000', 29.99,25),
       (4,22,'2016-08-01 00:00:00.000', '2016-12-31 23:59:59.000', NULL,NULL),
       (4,22,'2017-01-01 00:00:00.000', '2018-09-30 23:59:59.000', 39.99,28),
       (1,22,'2014-08-30 00:00:00.000', '2014-10-31 23:59:59.000', 39.99,28),
       (1,22,'2014-11-01 00:00:00.000', '2016-09-30 23:59:59.000', 20.99,15)

/* -- dates --*/
declare @fromdate datetime, @thrudate datetime;
select  @fromdate = min(start_date), @thrudate = max(end_date) from @t;
;with n as (select n from (values(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) t(n))
, dates as (
  select top (datediff(day, @fromdate, @thrudate)+1) 
      [Date]=convert(datetime,dateadd(day,row_number() over(order by (select 1))-1,@fromdate))
    , [End_Date]=convert(datetime,dateadd(second,-1,dateadd(day,row_number() over(order by (select 1)),@fromdate)))
  from n as deka cross join n as hecto cross join n as kilo
                 cross join n as tenK cross join n as hundredK
   order by [Date]
)
/* -- default price -- */
, cte as (
select 
    d.index_id
  , start_date = d.date
  , end_date   = d.end_date
  , t.gross_sales_price
  , t.net_sales_price
from (
  select dates.*
    , i.index_id
  from dates 
    cross join (select distinct index_id from @t) i
    ) d
  left join (select * from @t where store_id = 1) t
    on d.date >= t.start_date
   and d.date <= t.end_date
   and d.index_id = t.index_id
)
/* -- rows with a price */
select
    t.store_id
  , t.index_id
  , start_date = convert(char(23),t.start_date,121)
  , end_date   = convert(char(23),t.end_date,121)
  , gross_sales_price
  , net_sales_price
from @t t
where t.Gross_Sales_Price is not null
union all 
/* -- rows with with a null price */
select 
    t.store_id
  , t.index_id
  --, start_date = min(d.start_date)
  --, end_date   = max(d.end_date)
  , start_date = convert(char(23),min(d.start_date),121)
  , end_date   = convert(char(23),max(d.end_date),121)
  , gross_sales_price = d.gross_sales_price
  , net_sales_price = d.net_sales_price
from @t t
  left join cte d
    on t.index_id = d.index_id
   and d.start_date >= t.start_date 
   and d.end_date   <= t.end_date
where t.Gross_Sales_Price is null
group by 
    t.store_id, t.index_id, d.gross_sales_price, d.net_sales_price
order by store_id, index_id

View schema
Execution time: 0,17 sec, rows selected: 11, rows affected: 8, absolute service time: 0,31 sec