B.B.
Totally not rude for lemonade. We also will get a case of water and some sodas and let the kids sell those for 50 cents each - they usually go.
Great planning to do it at the same time as a neighbor. Multiple sales are really good attention grabbers. The last time we had one I also went around to neighbors close by and told them about it or stuck a flyer in their door if they weren't home, and we wound up with 13 sales in a close area.
As far as pricing, kids clothes are a dime a dozen. I usually will price things in good condition at $1.00, Jammies or 2 piece things for $1.50, the less nice things at 50 cents, and really nice things (never worn jeans or dresses, etc) at no more than $3.00. BUT, here in San Antonio, there are virtually 100's of sales every weekend, so I have to price stuff low if I want it to go. Adult clothing I price a little higher, but not much. I am of the opinion that I just want it gone. My mom prices stuff higher than I do , and her stuff winds up staying longer.
Toys are also a GREAT sell. I keep those between $1 and $3 unless it is something smazing.
Good Luck!!!