Let's Make Robots!

Which servos to buy for first walker robot

I'm planning to build a six-legged, 18-servo walker robot.  I'll start by perfecting a single leg and continue on from there.  I'll be using a board from my first project, Parallax's Boe-Bot.  Could anyone suggest a good, low-cost servo that I should use that's available in the USA.  I'm hoping to use servos that cost less than $5 each in order to keep the total cost down.