I was just at Once Upon a Child and paid $3-$4 for pjs (so one piece outfits), maybe $8 for a winter coat and $10 for a costume. I know the women here are bigger bargain hunters than me, but I thought that was pretty reasonable for things, especially in good shape.
It depends on how bad you want to sell them. I marked all my stuff as donate what doesn't sell so I'd rather sell stuff cheap than not sell it. There's a LOT of stuff at the sale for people to choose from. I've been to the sale 3x and I can't believe how much some of the women tag their used clothes at. Are you marking them available for the 50% off sale? I tried to make "outfits" as much as possible to save on hangers and not mess with so many low price items. I did like $4 an outfit. I had some carters fleece footed PJs and I used those clipey kind of hangers to "bundle" them 3 for $8. The winter coats are usually marked 8-10. The costumes are big sellers and are so expensive in stores right now. I'd see what they're selling for on like party city's website and mark them at half.
Re: how much would you pay?
I was just at Once Upon a Child and paid $3-$4 for pjs (so one piece outfits), maybe $8 for a winter coat and $10 for a costume. I know the women here are bigger bargain hunters than me, but I thought that was pretty reasonable for things, especially in good shape.