This is not the usual "Wine commune or winebid.com" question... though information on those is always useful.

I have a bottle of 1948 Petrus that I acquired from 1855.com when they were starting up; it was early in the dot bomb days, and I won an auction for the wine.  At that time, I paid $700 for the bottle.  I've decided that I will never open the bottle, and considering finances are currently tight I would like to sell it.  Prices on Wine-searcher range from $2095 to $9500 for a bottle.  Question is, how do I maximize my return on this single bottle?

Not necessarily guaranteed to "maximize", but should avoid "minimizing" your return...Sell it yourself but assign a Reserve price. Even though doing so will up your cost at the on-line auction sites, it is a small price to pay given the likely return.  The percentages charged at the big time auction houses will cost you a lot of dough if you go that route.

Find someone who is going to sell off a fair amount of wine through a traditional auction house and then piggyback your sale with his or hers.

Randy, perhaps through a local wine shop with whom you have a good relationship with? I know many wineshops often consign wines. I also have one in mind, I'll PM you.

I'd give Bert a call... he should be able to help.

I agree with Dan.  The piggyback approach should get you more attention and has the potential to lower your expenses if premiums are negotiated up front.