Given my current haircut... I'm no expert on hair products, but I'm a bit of a nerd. Basically if your dryer/straighteners are dual voltage, all you need is a plug socket converter. It will probably state the input voltage requirement on the product, it will say 110v - 240v is its dual, it will probably also show the power consumption in watts.
If its not dual voltage then you need a 240v step down converter, these are pretty cheap if you want a small one but the small ones are only capable of outputting around 100Watts, e.g a cheap set of straighteners like Ivana said. Expensive straighteners (especially turbo start ones) will usually draw more than this so they will probably melt a cheap converter. Blow dryers can consume over 2000 Watts, to safely step down the voltage and output that amount of power, you'd need a massive step down converter, the size and weight of a house brick.
I'd check your straighteners and see if they say the power consumption on them, then see if you can get a suitable step down converter. I'd forget the hair dryer and try and pick up a cheap one over here or borrow one from someone in your hostel. I'd imagine if you were in a female dorm it would be like a salon :p