I want to automatically add a currency symbol to each attribute in this field

33213321

select avg (price) as 'average_price'
from titles

I want to automatically add a currency symbol to each attribute in this field
For example
$ 12.30
How to add this $?

select '$' + avg (price) as 'average_price'
from titles
Can not do it

cv4bf5d65fd

select '$' + str (avg (price)) 'average_price'
from titles

cv4bf5d65fd

select '$' + rtrim (1) 'average_price'
from titles

cv4bf5d65fd

select '$' + rtirm (avg (price)) 'average_price'
from titles

fanfan1980

--try

select '$' + rtrim (avg (price)) as 'average_price'
from titles

wgfxman

select '$' + RTRIM (CAST (avg (price) AS CHAR (20))) 'average_price'
from titles