If tanking brings you joy and you can make ends meet without selling it, then keep it. If you need the cash, you need the cash.
You can get diffusers and bubble counters for a couple bucks each on eBay if you decide to keep it. DIY CO2 may be an option if you prefer to remain high-tech. Using champagne yeast could get you a couple months of CO2 power.
I've found that I need at least something to keep me occupied when times are tough. Since tanking is cheaper than going to the movies, paying for high-end cable packages and such? I'd pick the tank. I'd also go low-tech, as others suggested. Would sell the HC and get plants that require less effort.