Yup , it really depends on what you use it for , 30gb is a hell of a lot in text files and photos ect , but for films and games ect it isn't that big.
Also if it is used then i wouldn't buy it , in that case have a look here:
http://www.newegg.com/Product/Produc...SubCategory=14
A hole bunch of new HD's with 120/160 gb space between $50 and $75