i agree with dlf.. there's a reason there is an executive board, and a whole PTO body- there is no " I" " ME" or " MY" in "PTO". I agree in a positive approach to her, too. Thank her for her time this year, and tell her that her ideas are under consideration.
If she needs it spelled out, ask her to think about how the PTO would run if each person who donated money was allowed to say what exact item they wanted the money specifically used for. If she sees it through other eyes, she may be more receptive to understanding why her specific request can't be met.
and.. for the record.. you would be absolutely opening a can of worms... general rule of thumb never ever do something once for one group or teacher.. that you can't do for everyone...
here's an example that bit the last board ( not my board
) in the backside.. a teacher wanted sharpies.. no biggie, right? well, that $12 package of sharpies started a war about "favorite teacher- kissing up to board, etc" and other staff got mad ( petty, i know...).. so in the end.. the rest of them got their sharpies, and it cost the PTO an additional $400... a lesson that was passed on to me.. in what NOT to do when you think you are being nice!