I'm thinking about sold my Nintendo 3DS with Luma3DS and wonder how much I can get for 3DS with Luma3DS and R4 card with games?

Half +- few bucks from original price.
I live in Czech Republic, so I can push it high (because nobody knows here that you can hack 3ds).
Best option is to wait for offeres. Then you can "parley" about the price.