Hi! This is my first post here, although I've been reading for years

I was doing some work on my bike today and took the seat off and put it aside. After I was all done, I went to put the seat back and the quick release lever fell off into my hand. Whatever once attached the lever to the bolt's eyelet is now missing, and I have no idea where it went or what it was.

From what I can tell, it was just a small metal pin that held the lever on (there aren't any threads). So, should I go to my hardware store and find something of the same diameter, cut it to size, and wedge it in? Or just call my bike shop and pay for a new quick release? I've no idea what they cost. Are they proprietary? (It's a Specialized Hardrock MTB)

I'm not completely new to bicycle maintenence, but learning. I never would have dreamed one of these things would completely fall apart like that! It's only a year old, and it's not like I take my seat off every ride.

Thanks for any advice

edit: pic