Big fans of Deep Regrets, we really enjoy playing it and the 'Even Deeper' expansion. Love the randomness, the art, and the overall aesthetics.
One rule change we have been thinking of is changing the cost of the 3rd option in each shop to $6 for 5k2 (3 for supplies) instead of the printed $5.
Reasoning is simple, everyone does pretty much the same return to port, sell for $10 and purchase from both the rod and then reels deck. It seems to be the most efficient use of your time and money and the sheer amount of cards you get means you should have something of value for both.
This means the $1 and $3 are almost never used outside of the supplies and dice shops. Changing the cost to $6 forces you to be a little more strategic in the approach and it means the $6 option is still great because you get so much choice and can only shop at each shop once with your port actions.