Quote Originally Posted by Antonio1986 View Post
why the normal Сравнительная степень (i.e. светлее and дешевле) is not used instead of посветлее and подешевле in the sentences?
It can be used.
The form with по- is more colloquial, and it has a shade of meaning of ’a bit’. «Посветлее» — ‘a bit lighter’, «подешевле» — ‘a bit cheaper’.

Quote Originally Posted by Cumulus View Post
As far as I can remember, it's used to express "even ...":
громко = loud
громче = louder
погромче = even louder
I’d say that ‘even louder’ was «ещё громче» or «ещё погромче». Just «погромче» doesn’t have this meaning.


BTW, I don’t understand the sentence
Quote Originally Posted by Antonio1986 View Post
«У нас тоже что-нибудь подешевле»