Kidderminster sold there initial allocation of just under 400 tickets in 24 hours. They've now been given 300 tickets in the Chaddy End - I presume that's in just one section.
They probably didn't expect to sell as many away tickets. For example Kidderminster only took 183 supporters to Rochdale last month, and 181 supporters to York in August. It might only be £1 a ticket, but it'll cost them another £30 if they get here on the official coaches.