I was in a local antique shop the other day seeing if there's anything I could pick up as holiday gifts for friends and family. While there, I noticed about half a dozen straight razors in a display case priced between $20 and $40. I was going to ask the storekeeper to let me see them but realized I wouldn't know what I was looking at anyway (I'm a NooB to DE shaving but am interested in looking into SR). So, my question is, what are the general things to look for in a used/vintage SR to see if they're worth buying?