ebreh, i agree to use open source compiler like winAVR or wavasm for free.
But if you have some money, i suggest to buy codevision AVR its about 100-150 bucks. there's also a demo version, for free. browse to https://hpinfotech.ro
I agree using cvAVR because it is easy to use, powerful, and it support many chips from AVR and its cost is not very expensive.
try this link: https://www.dontronics.com
I have used both codevision and Imagecraft, I used 30 days version of imagecraft and I saw that it occupies a large volume of the flash for the same C program of codevision (and it was so bad), both of them have programmers and powerful instructions, but Imagecraft is more expensive. programming with them does't differ so much, I think that is better for you to use Codevision, you can download the trivial version from this site:
in Hong Kong, the IAR HK distributor said for student price, they can provide falh price. however, this company not yet reply me about the price.....
codevision, it seems ok although it is so unluck that my source code not yet able to complie.......(*but other groups of student able to do so*). i have e mail to one of the author who write book about AVR with codevision. he said it is the best.
so, i think IAR and codevision is good to consider, then iccAVR, then winAVR