Adding a Dollar $ to calculation from a CASE statement

case
when (tblbookin.bookindt between '2013-10-01 00:00:00.000' AND '2014-09-30 23:59:59.999') 
then '$'+Cast((DATEDIFF(DAY,tblbookin.bookindt,tblrelease.releaseddt)) * 62.46 as varchar(20))
when (tblbookin.bookindt between '2014-10-01 00:00:00.000' AND '2015-09-30 23:59:59.999') 
then '$'+Cast((DATEDIFF(DAY,tblbookin.bookindt,tblrelease.releaseddt)) * 63.11  as varchar(20))
end as [Cost]