If your message can be less than 255 characters, you might want to check out the extended stored procedure xp_sprintf. If you have ever done C programming, you will feel right at home with this stored proc.
Here is an example:
declare @variable1 nvarchar(10)
declare @variable2 nvarchar(10)
declare @message varchar(255)
set @variable1 = 'Betty'
set @variable2 = 'chili'
exec master..xp_sprintf @message output, 'Hi %s, do you like %s before 10:00 AM?', @variable1, @variable2
print @message
set @variable1 = 'Mike'
set @variable2 = 'Eggs'
exec master..xp_sprintf @message output, 'Hi %s, do you like %s before 10:00 AM?', @variable1, @variable2
print @message