What exactly is a kids consignment sale? Many churches, some mom's clubs, some non-profits and a few for-profit organizations hold community children's consignment sales twice a year (Spring and Fall) to allow families to sell gently used and new kids items
Most sales have one or more categories of qualifications to shop at the "pre-sales". Every sale sets it's own rules. Many require proof, like a current military ID. If you qualify or are willing to pay the early admission fee, you can get in ahead of the crowds and get first selection.
Most allow you to, but unless your kids are really well behaved, it isn't a good idea. Sale are often very crowded and the kids get in everyone's way. , and overwhelming for the little ones. There is rarely ever a childcare area at the sales.
Some sales allow strollers, some prohibit it completely, and some allow it only on certain days and hours. You've got to check with the specific sale.
Most sales are free to enter. Some have an early-admission (or pre-sale) fee. And a small number do have an admission fee at all times. When they have them, the regular admission fees typically range from $1 to $5.
All sales accept cash. Many take Visa, Mastercard, Discover, and Visa/MC based Debit cards, although there is often a fee to use them. Some take personal checks with ID, but many do not. Very few take American Express.