Use:
select t.id, sum(t.price)
, stuff((
select distinct ',' + cast(t2.ServiceID as varchar(max))
from @t t2
where t2.id = t.id
for xml path('')
), 1, 1, '')
from @t t
group by t.id
Output:
----------- --------------------- ---------------------
1 40,00 11,12
2 120,00 11