I have medium thickness blonde hair. My hair is naturally wavy and I straighten it quite often. I've had Revlon and Conair ones but I want a really good one.

I have about the same kind of hair as you do, however my hair is very thick.  I have always had trouble with straightening my hair is it actually being straight (always still had some wave to it, especially when it was humid out). I found a straightener about 3 years ago, and I absolutely LOVE it!  It is a remington wet 2 straight.  I actually got mine at walmart and it was very reasonably priced. 

Hello and thank you for using Imshopping! I have the same type of hair and i love my Chi Wet to Dry Iron available at http://www.Thebeautyplace.com for $138
The CHI Wet-to-Dry Iron is a state-of-the-art hair straightener, unparalleled in its performance. The auto digital feature allows you to set the temperature and the time, and the digital monitor allows you to see the temperature setting. Additional features include a timer with automatic shut off, ceramic plates, and ionic technology for smooth straightening, all from one versatile styling tool. Directions: Selecting temperature:

• The CHI Auto Digital Ceramic Flat Iron offers complete versatility for temperature setting. The controls allow you to set the temperature and the time.
• The digital monitor allows you to see the precise temperature for your requirements.
• You may also set a timer for automatic shut off when you are done with styling.

Using your CHI Auto-Digital Ceramic Flat Iron:

• Shampoo and Condition the hair with CHI Shampoos and Conditioners.
• Always make sure that your hair is 90-95% dry and combed through.
• Apply your CHI styling product to the hair (for example, CHI Iron Guard, CHI Shine Infusion, CHI Silk Infusion).
• Section the hair and start with a section approx. ½ inch (1 cm) in thickness.
• Start from underneath and work your way up.
• Thinner the section = more intense and thoroughly heat
• Thicker the section = less heat will be directed to the section