If you want to spend the money on real plants even though they'll probably be torn up, it's up to you. Right now in my RES's tank he's got all real plants---water hyacinth, duckweed, hornwort and anachris. The hyacinth and hornwort are from the stock tank he was in this summer. Rather than throw them out, they've been added to his tank until he either eats them or rips them up. He eats the duckweed and anachris. When the hyacinth and hornwort are gone, we'll switch over to some fake plants.

The same thing will happen with two of my painteds' tank. I have one painted, however, who has had most of the same hornwort in his tank for over a year now.
There are some realistic-looking plastic plants if you look. Once in the water most fake plants tend to look better. Your turtles won't mind if they're not real.

"You become responsible, forever, for what you have tamed." -Antoine de Saint Exupery-