I just bought a Marc by Marc Jacobs bag on eBay two days ago via "buy it now" and after a day of not getting any sort of shipping notification I finally received a message from the seller saying they are "out of town and won't be back for months" and then they canceled my purchase and refunded my money. I am so bummed about it. I can't find that same bag in the same very good condition except on Poshmark. I am a HUGE ebayer, I am constantly buying there, so using poshmark has me a little nervous. The seller I am looking at seems well liked... I don't even know what my point is (I can't sleep, it's 5:30am and I've been awake for 2 hours ) but I guess I need some reassurance before I spend $$$ on poshmark!
I've had a lot of success buying there but I have been scammed a few times too. When you go to her page click on "About" to see her selling history and to be sure I would ask for specific photos so she can take pictures to show the present condition. I had someone sell me a Tiffany bracelet that was old and broken but her photos showed a bracelet that looked new.
I would be cautious but I wouldn't worry too much though. Good luck.