When I found out it existed, I searched for about 2ish years until I found a New Year Promo card. I regretfully sold it over a year ago after I decided I wasn’t going to collect Jumbos but wish I had saved that one. I’ve been on the search again since.
I’ll trade you my mint copy to get graded for your Snapdos. 
XD In all seriousness, I’ll look at my extras and see if any qualify for a PSA 10. I’ll let you know.
Psa 10 masaki alakazam and gengar.
Searched 8 months and decided to sell the rest of 3 to fund other purchases. Next week the alakazam was for sale on virbank but the gengar didnt appear for another year.
Almost since I started collecting (2014) I was looking for a PSA 10 Plasma storm master set of the Ultra are and Secret Rares. Lugia FA was the one card that evaded me for the longest time. There was only 1 PSA 10 on the pop report forever and I never saw it pop up. I sell my collection and Now I found myself back in the hobby. my first week back there was a PSA 10 PS Lugia FA for auction which I won.
Another card I had trouble finding was a PSA 10 Team Magma Team Aqua ex. I was 4 cards away from all 128 and that card eluded me. Up until last week I had never seen one for sale. The person is asking $4999! It was around a Pop of 5 to 10 and now it’s 27.
Roughly 11 years
Spent 13 years trying to get a GS Rayqauaza 
Had multiple chances to buy em over the years but never had the money lol. Finally got one (in Psa 10!) two years ago off a member here.
About 8 years for this card. Now currently longest hunt is PSA 10 Staff Pre-release Fates Collide Tyranitar
Not so much searching, because there were always several copies available, but the PreRelease Clefable as well as the Black Star Promos #40 & #41 I took forever to pull the trigger on.
They weren’t cards that I was absolutely crazy about. I just needed them to complete my sets. I watched them for 2 years and finally realized the price was never going down. Learned a good lesson. Cards that are hard to get now will only be harder to get in the future and will be burn a hole in your wallet.
I have also been looking for a couple of the same cards for about a year now. They come up, but are way more than what I have in my planned budget/expected price for them, so I have passed. Sometimes this works out well, and I eventually have found the cards I want at a price I like with a ton of patience and time, but other times it has come back and bit me because the prices kept rising and I missed out on a card simply because it was at what I thought was an outrageous price when really it was just new market value.
A set i wanted to collect since the day i started collection like 7 years ago is still uncompleted and still will like to complete it maybe one day so 7 years to complete that set 
Still looking for PSA 10 Holo Unl Neo Discovery Houndoom and 1st Ed. I have to start searching for this a bit more heavily as it was never my top priority or another oppurtunity came up. Looking for 2 years (casually) now!
PSA 10 1st Edition Wigglytuff took me a minute.
This isn’t a card but a Pokémon item I was looking for. I’ve been looking since April 2018 for Polish Pokémon cards, which @pkmnflyingmaster helped me get some for Christmas (shout-out to him and his awesome finding skills) and then in March of this year, I actually found a seller based out of Poland selling some ex cards and thought what the heck, might as well see if she can help. And she was able too! She spent about a month tracking down sealed Polish Diamond and Pearl Theme Decks for me after I had spent almost 2 years looking for them myself and now they are happily in my collection 
Mjisaacs
I love hearing stories like this. Collectors helping other collectors is what this hobby should be about
Almost 4 years searching for a PSA 10 Squirtle Boundaries Crossed. I’ve bought so much bulk in hopes one would yield a 10 but no dice. It’s POP1 so my chances are low(ish) hahaha
I’m still waiting for psa 10 Kadabra base 2 to pop up…
Why is it just POP1? Due to it being a common card with low interest? Or because print quality/a lot of OC prints?
Seems like a bit of both. The majority of the cards I’ve purchased are slightly off centre but otherwise pretty minty fresh condition. And being that it’s a common I’d say there’s not much value for anyone to grade it unless they’re collecting a PSA 10 set
Still searching 5+ years for some cards in PSA 10, I try to grade as many cards myself in my collection
PSA 10 skyridge reverse holos lol. I might as well give up at this point on finishing these
Took me around 3 months to find a corrected blaine’s charizard