Fellow costumers, please help!

Ok.  I've got a problem.  I've got a $40 gift card and a 20% coupon (including sale items! you gotta love it!) to Joann Fabrics, and I DON'T KNOW WHAT TO BUY!!!  The coupon expires tomorrow.  I need ideas, please, please, please.  So, here's some possibilities.  On my to-sew list in slight order of importance....1) white 18th C. petticoat(s); 2) a quilted petticoat (is it wrong to buy pre-quilted fabric?  or is it just tacky?  or practical? LOL);  3) light grey-blue petticoat (to match both a white jacket and a blue one); 4) 18th c. ballgown (I don't even have any ideas on a color or fabric for that.).  5) Civil War ballgown;  6) one (ONE) Regency embroidered sheer ballgown (those are like the most amazing dresses ever, but when am I ever going to have a time to sew and embroider it? and where on earth would I wear it!  that does present a problem....).  My biggest problem is that I still don't have much experience when it comes to the feel of fabrics, their names, and what is historically accurate!  I need suggestions please!!!