I usually do not spend more than a dollar on any single card. I made an exception a few weeks ago when I bought the cards below. 401games was having their 1 millionth order contest - buy that day online, get entered to win one of a number of gift cards. So, I had little time, and a need to spend $50 - so I went a bit bigger than I usually do, but with a bit of purpose.
When I started, I grabbed the land card because I thought I might do my usual grab of many little things, but I changed that approach quickly.
The Disk card was the last artifact I needed for my Anthologies artifact set. While the same is true of the last couple Nemesis cards, including the almost $20 Tangle Wire.
The Blacker Lotus was most expensive at over $30 - and it may not be a Black Lotus - the Holy Grail of Magic cards - but it's a card I have always really liked, and is as close as I will get to the Black Lotus. Besides, it's just as pretty a card, if not prettier, just not as iconic.
Unfortunately, I didn't win one of the gift cards, but I do get to keep these which I may not have splurged on otherwise!