I do not have personal recommendations for curling irons as I don't use irons, but I will say you want one that has great temperature regulation (so it does not burn your hair which might mean paying more money). I picked up a second-hand dyson blow dryer a while back because of the temperature regulation on it, it never burned my hair but I did feel like it was hot even on low so I had to move it around a lot. You always want to use a heat protection product when using high heat (which curling irons, flat irons, etc. do). It should say it protects up to 400Β° F, I believe 266Β° F is the temperature when hair actually burns. I tried the CHI products and liked it, these products will generally have silicone or something else with low thermal conductivities to protect your hair. Look for something made for flat ironing.
I follow lab muffin a lot (this is her article on heat protectants), and it does seem like your hair will still get damaged this way. I use K18 which might help your hair feel less damaged, my hair is just naturally fragile so I use it. My hair is curly, I find that heatless curl methods make it more wavy but I am not sure if they work on straight hair.