https://itsdeductibleonline.intuit.com/help/condition.html#1
Here's how 'it's deductible' defines "high value" vs "medium value".
As far as clothes, you can look at some online thrift stores (Thread Up, Swap, Re-Stitch, etc) and get FMV (fair market value) there as well. I find this a little quicker than e-bay for clothes. Also, just because something is 'new with tags', doesn't mean it's high value. If something has been sitting around for a long time, and it's just not in style at all anymore, this should probably be 'medium value'. A gently used, recently purchased prom dress is going to be worth more than a new prom dress with tags, from the 80's.
