Be careful on eBay... I tossed my Speedmaster 57 up there last night and it sold in two hours. Luckily I'm not a complete dummy and checked the buyer. New account with 0 feedback and 0 history of anything. I instantly called eBay on the phone. They walked me through a cancelation process and even helped me set my account so people with negative or no feedback will be automatically blocked from my sales. I tell you this story as a seller beware...
Honestly, take out a care credit card and pay the dentist off slowly. The hit you will take for the watch is not worth it. Also that watch seems like it had some real sentimental value, don't lose that.
My 2 cents