and usually, when i use the "POA". it's purpose is three fold
1) it's a rare item and obviously going to be priced strongly, which means it may be awhile before it sells. Because of that lengthy sale period, market value may go up (hopefully) or down, in which case i can adjust that price "on the fly". If i've committed to a fixed price, and market goes up and i forget to adjust my posted price, i have no choice but to sell at that posted price.
2) some privacy or confidentiality for the eventual buyer - obviously a rare watch is going to be noticed by a number of collectors, whether they're actually in the market or not, and when it does sell, the actual purchaser would probably prefer others didn't know how much he /she paid. A lot of times because they know other collectors will judge them foolish for having paid "so much" - those buyers that will pay the premium price are usually buyers with ample disposable income and actually more disposable income than disposable time, so to them the "premium" of looking longer and waiting for other selections of that item to come up is more expensive to them. 2nd, they recognize that waiting for another one, better priced may not happen and by the time they do see another one, market value has gone up further - but the other collectors will not take that factor into account when judging the purchaser "foolish" for having paid a premium
3rd) i'll admit i pioneer new price levels on the items i offer - buyers will and have paid me 20%+ more for an item my competition is offering because they know me, and know i will deliver what was described with no shenanigans and will be there in the event there is a problem (dis-satisfaction with product etc)
4th) i do not care to tell my competition what i am getting for an item - a) some will try to compete by discounting my price, which in my mind isn't selling but rather giving it away, 2ndly, if they dont know the new value level i've established, it might give me the chance to buy from them at yesterday's price, or have the advantage value wise, in a trade with them
i know seeing POA has to be aggravating to a lot, but it also serves as a screening of customers who are only tire kickers - people that still inquire are ready for a strong price, but by their inquiring have told me they are interested in the product offered.