Yard sale season is in full swing, giving meaning to the saying "one man's trash is another man's treasure." While you find great deals and treasures at your weekend yard sale, there are some things you shouldn't haggle over, especially when it comes to your kids.

Even though car seats are pricy, don't buy one at a garage sale to save some money.

"Car seats are designed to only protect your child in one accident," said Geisinger pediatrician Michael E. Ryan, DO, noting that car seats that have been involved in accidents may not have visible damage. "You need to buy a new car seat to ensure your child has full protection in the car."

The plastic of the car seats can become brittle with age and older models may not meet current safety regulations or may have been recalled. Plus, car seat technology is constantly improving - buying a used car seat at a yard sale could compromise your child's safety.

Similarly, skip over bike helmets at the next garage sale - they too are only designed to protect you from one accident and damage may not be evident.

Cribs are another no-no at yard sales.

"With crib safety standards always changing and recalls regularly announced, you simply can't verify the safety of a used crib," Dr. Ryan said.

And you should never buy a crib built before 2011, when new manufacturing regulations were put in place and essentially made cribs built before that year obsolete.

"Drop-side cribs used to be the most common type of crib used, but they're particularly dangerous," Dr. Ryan said. Older cribs may have slats with wider spacing than regulation allows and you may not be able to tell whether there are issues with the hardware or how the crib was assembled - a crib with missing or damaged pieces is at risk of collapsing.

"In the past five years, cribs, bassinets, infant swings, bed rails, and infant or toddler play yards have experienced recalls," Dr. Ryan said. "Recalled items pose a life-threatening risk to infants and children - don't take a chance on buying any of these used at a yard sale."

If you have a baby who is still breastfeeding or feeding from a bottle, you could likely always use more baby bottles - but do not buy any from a yard sale.

"There's always a risk of cracks and sanitation issues with baby bottles, but most older bottles contain the chemical BPA," Dr. Ryan said. As of June 2012, the Food and Drug Administration (FDA) no longer accepts that as safe.

Toys are common at garage sales, but proceed with caution.

"Toys occasionally get recalled whether it's due to breakable parts, choking hazards, or lead paint," Dr. Ryan said. Unless you or the seller has checked the Consumer Product Safety Commissions' website, you may have no idea a toy was recalled.

If you do buy toys - or clothes - at a yard sale, thoroughly wash and disinfect them before giving them to your child. Stuffed animals are tricky - try putting them in your washing machine on the extra hot cycle to ensure they don't have anything unsavory on or in them.