Du kan prøve dette:
'$' || Cast((select avg(retail) from cars
where brand = 'FORD' or brand = 'TOYOTA') as decimal(4,2)) as AVG_BRAND_PRICE_01
Hvis du vil have mere end $XX.XX, f.eks. $XXXXXXXX.XX, skal du sætte decimalen højere, f.eks. decimal(9,2)
Eksempel SQL Fiddle:http://www.sqlfiddle.com/#!4 /9f684/2/0