I hate garage sales. People always want something for nothing and I get inslulted to put GOOD quality items out for nearly nothing anyway just to have someone try to get it much cheaper. (EX...I had my 12 yr olds gently worn Abercrombie clothes out for sale and I was offered $2 for a $50 pair of jeans, etc.) I thought I was generous to ask $10 and under for the items.
My hubby is a numbers man (MBA from Duke) and this is calculated carefully. When you take into consideration of the money made at the garage sale vs tax benefit....keep in mind YOUR time spent at the garage sale. YOUR time is worth a lot as well.
I am very detail oriented. For tax purposes, I take pictures of items I have donated in case IRS wants to see something. We donate to the women's shelter in Plano mostly (washer/dryer, computers, tv's, furniture) and clothing items go to Goodwill. I keep all the donation receipts in my tax file.