Not being able to go on land would be pretty bad. Idk it depends on what the company on the ship is like, the quality of my quarters, etc. If this includes moderate physical labor or regular PT or something the cost would actually go down. For enjoyable company plus my own room plus physical labor/PT plus internet plus all my basic needs provided, $30k to feel good about it.
You’d be surprised how good the food is at sea (if you’re sailing with any kind of respectable line e.g. MÆRSK) because there is fuck all to do at sea. Bring books. Bring a laptop and get some writing done on the book you never had time to work on. However, if the internet is for gaming you can 100% forget about “plus internet” because there are no cell towers at sea. Satellite-based data plans charge $$$ compared to landline internet,* the example I found last I checked was $50/month for 50 gigs, I don’t know if prices have fallen (better tech, more satellites) or or risen (more users) since then and, while their bandwidth capacity is OK, their ping is atrocious. If it’s just for browsing tumblr, you might be OK.
*Still cheaper than US “Cellphone” “Roaming” “Data” “Plans” but eh, gold-plated jets are cheaper than US cell plans