Entry will be just £5 for all except for under-11s who will be allowed in for just £1.
The plan is to give the team the boost it needs to progress in the famous competition.
Fans played a vital part in helping Reds to hold Southend to a 1-1 draw, thanks to an 85th minute own goal equaliser.
The result forced the two sides to meet again next at Tuesday’s (November 20) replay at Broadfield Stadium.
Operations director Kelly Derham revealed: “I feel we need to push the whole town to help the boys.
“In the second half on Saturday the whole crowd was absolutely amazing.
“We are going to try to to get as many as possible in as it gives the boys so much confidence - the singing really works.
“We hope this will push them through to the next round.
“We had 2,00 when we played Bristol Rovers in a replay in November 2016 so with the reduced price if we could get 3,000 here I would be very happy.
“Tuesday nights are always quite difficult but i believe there is no other football on that night.
“The fans (323 of them) were so good at Southend, we just need that atmosphere again. it could be the start of a good run!
“I’d like to thank Southend United who were happy to agree to the price cut.”
The winners of this first round replay will win £32,000 prize money and will enjoy a valuable home tie in the second round against League One club Barnsley.
Tickets went on sale for the Southend tie at the club at 12 noon today.