Best curling iron for super straight hair?

I have incredibly straight hair. Nothing affects it - not rain, or humidity, or anything. It's always just stick straight. It's not just one thickness, either - if you take a handful of my hair (when it's its natural colour), you'll find that no two hairs are the same shade. They range from super blonde to black. The blonde hairs and very fine whereas the black hairs are very thick. My hair is also quite long, currently at my waist when behind my back. The curling iron I've had for the past couple of years is my mom's old Conair, and it sucks. I have to hold it for 4 minutes (literally, I wait for a song's length) on one strand of hair to get a shadow of a curl. And the curls fall out after about half an hour. Now, I went to a university fair a week ago and the hair school was curling people's hair, so I went and got mine done. It took her 6 minutes to do my whole head in these big, loose curls. They fell out 10 minutes later, but that could be fixed with some hair products. So it CAN be done, it's not that my hair won't respond to curling in general. ANYWAY. I'm going to the mall today and I'm going to buy a new curling iron. What would you suggest for me to get? Something that works quickly on long, straight hair. Also, what kinds of hair products should I get to keep the curls in place all day once I've got them? Thanks!