I did this recently with Preemie girl clothes for my Sister in law. My niece was born 10 weeks early and only weighed 2 lbs, 1 oz. I knew she would need clothes eventually (they have them in diaper only for several weeks in the NICU), and I was trying to be helpful, so started shopping locally and looked on Craigslist as well. I had never bought much on craigslist...bigger things (costly) like cell phones and such.
I saw an ad, replied and such, but she had 4 separate preemie outfits for a dollar each. I took all of them and she met me close by (it was on her way to a church event, so worked for both of us..sorta weird handing over $4 in parking lot..LOL). But then I placed my own ad..WANTED..one of those. A gal replied and she had a "lot" of preemie girl things for $20..another great deal..she sent me pics and I zoomed in and they looked great (I was looking for formula stains, etc). Turned out she lived a few blocks from a relative of mine who I would be seeing that weekend at this SIL's baby shower (but about an hour from my own home). So arrangements were made for my relative to pay for and pick up the items.
They were fantastic! 2 still had tags..she put them in a baby gift bag she had (used) with tissue and all. We had emailed several times and she knew I would be seeing my SIL at the shower and giving them to her then (not as a gift, but she washed and presented them this way for me)..so nice! They were immaculate clothes and cheap for me to help my SIL and tiny niece has a killer wardrobe now! LOL
So...my experience so far has all been positive, albeit limited.....and I like the "lot" idea much better. If the price is decent, you can toss or donate the few things that won't fit or be your taste, etc.