You really need to think about what will make your child happy, what will keep them safe, what will interest them, what will keep them busy and what they really want. Kids often want toys that are not appropriate for them or are too expensive for the parent to buy.
Toys are programmed into kids' minds telling them what is 'cool' at the moment, what colors they should be wanting, how big or fast what is pretty and what is designer. These are a lot of things for kids to think about and they often follow the latest craze in fashion just to fit in and feel 'normal'.
Parents also feel the pressure of adolescence though some fight to the end to have their child be a nonconformist and begin new trends. Neither is theoretically bad for the child and actually cerates oportunities for the child's personality to shine.
Boys and girls are programmed by all forms of media and society to like certain colors, watch set TV shows and play with particular toys. Most girls toys seem to be in the white, pink, purple, yellow, maybe light blue range of colors whereas boys toys tend to fall into the colors red, black, green, orange, brown and yellow.
Parents are forced, by love for their children, to follow a vast majority of the trends set in color coded toys. If you think about popular TV shows and the characters portrayed - what do they wear? The princess in the tower wears a dress of stereotypically girls colors and the Prince is dressed in the colors that are normally associated with boys.
Because children generally choose their toys from magazines or based upon TV or Movie characters it's easy to research the toy, where to buy it, which other toys are associated with it and of course the cost. With all this information for the parent the job should seem rather unmenacing. The only thing left to think of is if the trend will change before the child receives the toy. It's hard to tell when the season changes on a toy and if it will come back into your life again on DVD part two but what you can be sure of is that if you choose a toy your child really truly likes, it doesn't matter what the shelf life it has for other children - your child will treasure it because you took the time to think it over carefully.