Addicted to smelling used panties

I'm addicted to smelling used panties. I'm so damn upset that I'm not better friends with more women, because it's a serious pain in the ass getting this horny over something so incredibly elusive. Buying them online is an option I suppose, but it's just so much better from a girls whom I actually know. Maybe it's the secret. Who knows when it really started, but I think my obsession with the scent of a girl's ass and pussy really took off back in my senior year.
My girlfriend at the time would often stay the night at my house, and of course some of those nights we wouldn't have sex. A horny 17 year old lucky enough to have a babe in his bed, I would occasionally spoon her with my hand cupping her butt until she fell asleep. After administering several makeshift tests to make sure she wouldnt be roused by any subtle motion I made, I would begin to ever-so-slightly slip a finger or two underneath the crotch-strap of her underwear.
I'm positive to this day that she never once was aware of any of this. My hand already between her butt-cheeks I would carefully massage the opening of her pussy until its dampness lubricated my finger enough to slip just the tip of it in.
Moving on to her puckered little butthole, I could never quite get my finger inside. After switching from ass to pussy, ass to pussy for a few passes or so, I'd gently remove my hand and deeply inhale. The scent drove me wild, and I would furiously masturbate in the next room every single time. It was absolutely heavenly to me, yet for some reason I never had the sense to steal any underwear!
Jump ahead a few years. I'm a college freshman living in an apartment with two friends; one female. One day, as I'm jacking off in the living room, home alone, I noticed the door to her room left wide open, directly in front of me about 15 feet away. With a raging erection, I crept inside.
There on top of all the dirty clothes in her hamper lay a neon pink thong, a black fullback panty, and on the floor there sat another thong, lacey and purple. I picked up the pink one, fapping, and stared at the very light discoloration of its crotch area. A slender, petite, gorgeous 22 year old white-girl had this quite pourous cloth wedged up against her sweaty twat and ass for hours and hours at a time, her tan cheeks shifting it back and forth as she walked and sat down throughout the day.
I took a deep whiff, and took many more as I breathed through the bottom of her thong. I doubt that my cock will ever swell to that size ever again; it was as if she had shoved her naked ass directly in my salivating face. The sweet, sugary musk of her pussy mixed beautifully with the robust and pungent acidic smell of her ass, and each pair had a different combination of ass, pussy, and sweat (with just the slightest trace of pee). This variety drove me totally bonkers, to a fiendish level, but unfortunately she moved out before I could do this more than 5 or 6 times (her moving was totally unrelated; she definitely does NOT know).
Since then, I've only been able to "score" a single pair, which I wasn't able to keep. It was a pair of white satin panties that I took out of my obscenely sexy friend's backpack while camping with a few others. Her smell was very much different from the last girl whose privates I'd secretly known like this; much more on the assy side and distributed across a wider area of cloth, which worked perfectly for me since her ass was far more round and attractive than my roommate's. I fapped in a butt-induced trance of hedonistic glory-love before cumming some more buckets, and lamented in sadness while I carefully returned the undies to her bag. The next day was quite interesting, for me at least.
I want more, god welding dammit. I'm good, old friends with a beautiful thong-wearing girl with whom I often smoke the weeds. All decency, integrity, and mutual respect aside, I want so badly to yank a pair out of her dirty laundry quickly while she's in the bathroom or something. I don't want to spend money on panties that might lose their scent in the mail. How can I get some more?