If you start working towards it, I believe a Living Ship can be obtained in a week at the fastest. They're not great for S-rank ships, but they do have massive inventories and are very cheap to run. Meanwhile, if you save up, grab the first Exotic you like, since they're essentially the baseline "high average" you measure every other ship against. Interceptors can be acquired for "free" by locating one and doing a short fetch quest.
Also, once you're deep into the game and can afford to class-up a ship, finding any C-class ship and upclassing it makes it the best ship, so hang on to anything you like the look of. Credits also become trivial once you can make agricultural operations and break open depots, which opens up the process of buying and scrapping Vy'keen fighters for nanites and inventory expansions.
Mechanical spoilers for ideas on saving up for your first Exotic:
spoiler
There's a few money makers you have access to early. Salvaging crashed Haulers in 3* economy Gek systems is extremely fast and will get you an Exotic in no time, but salvaging ships anywhere will work well. Raiding Supply Depots and crafting the loot up into higher-value trade goods is a moderate all-rounder farm. Setting up an agricultural project in a base is also good, either use it to support crafting or just grow cash crops directly. Finally if you want to venture into civilisation space, there are player farms around; ones specialising in illegal goods are a decent way of getting initial funds.
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