I'm considering a 5k card

[Casey2296]

If you want a tip on short term investing/flipping I don't have any intelligent advice for you. As a collector, I think you have it backwards. It’s good that you want to acquire quality cards, smart move as they will always hold their value. I'm also assuming you are talking post war because you posted here.
I would suggest that you start exploring what players, sets, cards strike a cord with you personally, do some research on them and then watch the market. For example, the first card I ever paid big money for was a 4.5 54 Wilson Franks Ted Williams, I watched the market for 6 months, learned and waited, when the right one came along I knew it immediately and bought it. It's rare and imo one of the best Williams cards out there so I enjoy having it in my collection no matter what I paid for it. The fact that it's worth more than what I paid for it is icing on the cake. I would have regretted buying a lesser copy.

Prioritize what you really want and what you want your collection to look like. Never buy a card that doesn't excite you just because someone tells you it's a good investment. Make a list, you'll have plenty of opportunities to spend 5k on a great card from that list.

Good luck and happy collecting!