Translation:I bought new dresses for myself while I was in Ankara.
"Kendim için aldım-I bought for myself" vs "kendim aldım-I bought myself" is the difference I think. You can report any translation disputes and we'll go over them.
I'm sure ''I bought myself new dresses while I was in Ankara' should be accepted.
If "I bought myself" is followed by a noun phrase, then it means the same as "I bought for myself".
(My Turkish is not good enough to recognise whether "kendim aldım" ever means "kendim için aldım".)
Isn't "kendim aldım" "I myself bought" (i.e. I bought them, not anyone else) rather than "I bought myself" (i.e. I bought for myself)?
I understand "I bought myself" (in English) only as meaning "I bought for myself". Since you can say "I bought her a dress" but you cannot say "I bought me a dress" and it has to be "I bought myself a dress" instead.
Can we also use "kendime" instead of "Kendim için" ?
And what is the difference of meaning between "elbiseler" without accusative ending, and just "elbise" ?
Regarding the first question: Yes, surely you can.
For the second one: 'Elbiseler' is plural form of 'elbise'.