I took my daughter last year - we stood in line at the Wal-Mart Supercenter for the gameboy SP's. We were inside and dressed appropriately as well. She will be going with me again this year - she is a momma's girl.
I agree with the majority - you are the one that knows your 13 year old. If he/she is mature enough then go for it. I have had my cousin who is 14 babysit a couple of times and let me tell you - she is tough, LOL. The car thing would have been tough because no kid wants to sit in their carseat when the car isn't moving and that would be the only safe way to contain the younger kids - home is perfect, they will probably sleep the whole time anyway. Just start practicing the morning routine with your 13 yo now to have him/her ready.
I understand the need to get out and get the good deals. I know some have said that there will be more sales - but BF have the BEST sales with some items at the cheapest prices they will be for the season. The fact is that some of us NEED those cheap prices to be able to spread our cash to provide for our kids & family.