SQL error in create table

Every time I try to run the create.sql file I have, it says there is a syntax error near "buy_price". The rest of the tables work fine, though.

create table Item (itemID string PRIMARY KEY, 
    name string, 
    currently string, 
    buy_price string, 
    first_bid string, 
    started string, 
    ends string, 
    userID string references User, 
    description string, 
    constraint ch_buy_price check buy_price >= first_bid,
    constraint );

Any help would be appreciated.