My advice would be to try and sell your pipe for the highest price you think it's worth on a site like e-bay first. Use the buy it now option and be patient. Great pictures are important.
If it doesn't sell after a month or so, then look into these types of commission sales. They're a great service if you need them.
But... they need to make money, and so, they will price it a significant amount under the market value, because they're not a charity for you. Everyone knows this going in. If you had no takers on your initial attempt, perhaps it's now worth it.
I rarely sell pipes. My experience was this. I contacted them, got a maximum price for what they would pay for it under the best conditions and decided to list it myself. I just sold my pipe for $250 more than I would have got from using them. They didn't "low ball" my pipe. It's just business. They need to make a profit from the exchange.
Maybe I got lucky by selling it on my own.
But, if I had to do it again, they would be a last resort. It's not that I wouldn't ever use them, I just think that it's worthwhile to at least try on your own first, assuming you have an idea of how much you are willing to sell your pipe for. And if you need great pictures, find some local amateur or student and fork over $20. I think many people can get a good deal on their own, with some effort and patience.