Ala. Code § 23-1-92

No contract where the estimated cost of the work will exceed $250.00 shall be made except after advertisement for 30 days in some newspaper published in the county, describing the character of the work to be done and the time and place of letting, and then only to the lowest reasonable and responsible bidder for such work, who shall enter into bond in double the amount of such bid, conditioned for the proper performance of such contract according to the plans and specifications and within the time prescribed by the order of the county commission of such work, which bond shall be approved by the judge of probate of said county. Where the estimated cost of the work exceeds $2,500.00, advertisement as above must also be made in a daily paper published in this state of at least 5,000 daily circulation once a week for 30 days. The county commission shall have the right to reject any or all bids.