I have a few memorable purchases.
The first time I got a round 50 was back in primary school, I swapped a Hong Kong bimetallic $10 coin for my friend's round 50. He told me his family had some at home and was willing to do a swap. I had never seen a round 50 before, and he had never seen a bimetallic coin before. When I got it I was enthralled! My 12 year old self thought it was the most fascinating thing to see a round 50 cent coin. Also at the time I had no idea what real silver actually was, it was only after I realised that the round 50 was 80% silver that looking back now I think I got quite a deal in the swap.
First silver purchase was a Perth Mint 1kg bar. Silver had come back down from the $49 high, it was still around $35 and oz at the time when I bought it. Had no idea where or how to purchase silver, and a google search lead me to the Perth Mint. Ordered directly from them, paid through the nose for the premium and shipping. It arrived a few days later, I still distinctly remember the strange sensation of holding something so dense in my hands. That bar has since long moved on, I swapped it on here for some numi coins, most of which have been flipped. Still managed to break even on the bar by flipping the numis, even after watching silver drop all the way to the mid $20s throughout the whole process.
Best purchase was a lot of predecimal silver on eBay. The listing had only a couple of photos of the lot, but interestingly there was a 1934/35 Commemorative in the mix. Knowing there are many fakes out there, and the photo not being very clear of all the coins, I pulled the trigger anyway on the ~$20 buy it now price. Received it a few days later and lo and behold, the 1934/35 Melbourne Centenary Florin was the real deal. Couldn't believe my luck.