It depends when it was manufactured. If it is a recent model, it should have the "better" trigger, as S&W has incorporated the "Shield like trigger pull" into all the M&P models, except I don't think the M&P 45 models have the better pull. The "Shield" pull has the audible and tactile trigger reset. Since your looking at a 9C, if it is a newer gun it should have the tactile reset, if that gun is not a "New Old Stock". S&W announced back in March 2013 that the M&P's now have a " Positive, Tactile Trigger Reset", in an advertisement for the M&P pistols in Guns and Ammo Magazine.
That does not mean that the pull will be super smooth, as my Shield had a very gritty trigger pull and I found that S&W had left a large machining burr in the striker blocker bore of my Shield. This caused the gritty pull in my gun. When I removed that burr from the bore, the pull went to very smooth.
I have bought and sold many handguns and rifles through Gunbroker, with only one issue, I got a Browning Buckmark 22LR Pistol, that was listed as new. When I received it, the pistol was unfired but it was a 5 years old model, by the serial number. It had been sitting on a shelf for 5 years???? The dealer that sold it would allow me to return it and get a full refund, as it was the only Buckmark he had. I kept it as the new manufactured Buckmarks were identical (no changes of any kind). I got it for about half the retail price and it is a really nice gun with SS barrel and slide, and it is very accurate.
You can really see what a particular gun is worth on Gunbroker, when you search for completed auctions, and check the sold prices. Click on the advanced search button, choose the "Completed Items Tab", at the top. Then type in the gun you are checking for in the "Search Words box", example enter "M&P 9C". I usually then go to the bottom and change the "Sort By" to "Newest Items First". That way page one shows the most recently ended auctions and subsequent pages are older auctions. Otherwise you would have to go to the last page to see the most recently ended auction. Check the date that the auction ended.
The value of a gun or anything else is what the average selling price is, forget about what the starting price is. Many sellers have no idea what the value of their gun is and often have ridiculously high starting prices, higher than the actual selling price would be, and they never get a single bid. This true for guns, ammunition, etc. You have to determine what you are willing to spend, and bid to that amount. You can get some good deals, but you also will see you lose out on an item by what appears to be only a few dollars. I say what appears because if you continued to bid, the opposing bidder may also go higher. The problem with bidding higher than you set, is you never know who you are bidding against. That person may also keep bidding and the bidding can get out of hand and end up much higher than it should have been. "Buy Now" pricing is great, if the price is right, as you get it for the buy now price and end the bid process.
Bob