You can buy these chips at most any electronic parts place, I bought the 75HC244 at Fry's $1.89 which si HIGH, Mouser.com has them for like .59 cents i think.

Radio Shack carries some chips but not sure on these or something that would work, you need a Non-Inverting logic chip.

The 244 and 541 are Octal chips, ONE chip will operate 8 servos.

Very common chip.

Smart Fly, I agree, we tested one and the output SIGNAL voltages were 4.8 v p-p. We didnt check the min input signal, they use the hct 541 chip and the HCT series states 4.5-5.5 so im not sure about that.

To me the HC series would have been a better choice but theres MANY different chips that would work fine.