With all being said, if you can't afford to pay for the transaction fee when using the Atm and same time doesn't want to use the exchange due to security reasons, then you'll have no other choice than seek for one who's willing to sell his or her bitcoin so, you're likely dealing on one-on-one transactions with the seller where you'll be sent the amount of available or desired bitcoin by the seller directly to your Dex wallet while you sent the money to the person.
Note, there might be a breach of smooth transactions here since there isn't going to be and escrow.
So, you got to be careful and do your best to deal with a sincere person.