[cgreerrun]

I haven't personally, but I know people that have. The people that I know that sold shares used Equity Zen (https://equityzen.com/). The company I worked for has/had a "first right of refusal" option in the equity contracts, which basically means that when EquityZen offers you a deal, you have to bring the deal to your company and they can decide to buy your shares for the same price instead of letting you sell your shares to an outside party (which they might not want).