Oh, is there anything more tragically overpriced than those vinyl stripper costumes in the porn store? Or the slightly more polyester versions sold at Ricky's during Halloween? I guess if you don't mind the possibility of wearing something someone has puked on, you could check out Craigslist on November 1st and see who is selling.
But, I mean, I think you can just half-ass it. It's not like he's the lady who did the costumes on Elizabeth or anything, right? (Alexandra Byrne, duh.) Pretend you are the sorority girl Halloween version of Stacy and Clinton: stock up on a few slutty basics like a supertight pencil skirt, tight-fitting button-down shirt, supershort pleated skirt, stripper heels, garter belt and thigh-highs, glasses, etc. Then mix and match that shit. Dress-up party!
Alternately, you could check out thrift stores for things that can be slutty costume-able, or spend some time online at cosplay sites. There are very detailed plans and instructions for sewing/creating beautiful and elaborate cosplay/steampunk gear all over the internet. Though it is not my cup of tea sartorially, I really have to give those steampunks their due—they make some amazing stuff.
Honestly though, unless this is something that you're also excited about, I would not put a whole lotta effort into verisimilitude. Were it me, I would just as happily get my "prostate exam" from a sexy nurse in a tight dress she already owned and a cheap toy stethoscope from Duane Reade as from a sexy nurse in a $400 pleather Nurse Ratched dominatrix outfit. And if he does have a problem with it, well, perhaps that is an expense that he can be in charge of from here on out. I would be sad if you couldn't afford to retire because all of your 401(k) money had been invested in rubber bustiers.
Perhaps you can settle a completely hypothetical argument. When a single person is sleeping with someone who is cheating on their partner/spouse, is the single person also a cheater? I say no, that you can't be an adulterer or whatever unless you're with someone, but my friend swears that both people are cheaters. What do you think?
New York defines an adulterer as a person who "engages in sexual intercourse with another person at a time when he has a living spouse, or the other person has a living spouse."
So I guess legally your friend is right? Weird! I still don't completely understand that! I mean we can debate the possible moral iffyness of fucking someone you know is partnered but I thought you definitely had to have a spouse (or equivalent) to be an adulterer. Looks like we are both wrong, question-writer. Though I still don't totally get why. Lawyers? Biblical scholars? Any thoughts?