So I just found a thing where a guy dug up an official list of suggested prices for all things shipowner, out of Galaxy Guide 6. As with everything credit-related, take this with a grain of salt, and much of it's tweaked for RPG use. I'm especially dubious about the CGT price. But overall, this thing's great.

MUNDANE COSTS​
Docking fees
These vary from spaceport to spaceport, but most spaceport Standard class or larger charge 50 credits per day. A busy Imperial Class spaceport might charge 150 credits a day

Standard Maintenance and restocking:
Standard restock includes replenishment for all fluids - water, lubricants, coolants and oxygen. Also included are basic proteins for autochefs, but not luxury items like fresh food or liquor.
Cost is a flat fee depending on the total crew and passenger capacity of the ship times the "consumables" in days (10 x Total capacity x Consumables)
Fuel
Spaceports can equipped with fusion generators that recharge fuel cells. At the slowest rate of charge, this costs next to nothing, but if called upon to recharge quickly, the costs increase rapidly. The following costs reflects most Standard Class star ports. It is likely to be cheaper at better class ports and more expensive at more primitive ports:
Charging Rate - Cost per cell
Trickle (1 cell/day) - 5 credits
Standard (1 cell/hour) - 10 credits
Fast (4 cells/hour) - 50 credits
Emergency (20 cells/hour) - 500 credits
Most stock light freighters are equipped with 50 fuel cells. Additional Fuel Cells: 500 credits each. One cell of fuel is used for:
* Entering Hyperspace
* Six hours in Hyperspace
* One month realspace operation
* One hour combat maneuvers
* One hour atmospheric flight

EQUIPMENT​
Hyperdrive
1/2 - Not available to civilian ships, 30,000 on the black market plus 2,000 instillation costs
x1 - cost: 15,000 Credits.
x2 - cost: 10,000 Credits.
x3 - cost: 7,000 Credits.
x4 - cost: 4,000 Credits.
x5 - cost: 2,500 Credits.

It is possible to remove the backup hyperdrive and sell it (price: 800 credits), gaining additional cargo space
After every twenty hyperspace jumps, the ship should have a complete overhaul and tune-up, with certain components replaced. Cost: 1,000 credits
Sensors
Electro-Photo receptors: 300 credits
Full spectrum transceivers: 500 credits
Dedicated energy receptors: 600 credits
Crystal Gravefield Traps: 3,000 credits
Hyperwave Signal Interceptors: 2,000 credits
Life Form Indicators: 800 credits
Sensor Jammer - 1,500 credits
Sensor Decoys - 1,000 credits
Weapons
Blaster cannon - 1,000 credits
Laser canon - 1,500 credits
Heavy Laser canon: 3,000 credits
Turbolasers: 9,000 credits
Light Ion Canons: 1,000 credits
Medium Ion Canons: 1,500 credits
Heavy Ion Canons: 3,000 credits
Proton Torpedoes
Firing system: 2,500 credits
Torpedo load: 800 credits each
Concussion missiles:
Firing system: 3,500 credits
Missile load: 500 credits each
Fuel converters:
Solid Fuel Converter: 8,000 credits
Fuel Scoop: 15,000 credits
Solar Converter: 12,000credits
Miscellaneous
Concealed Cargo compartments: 200 credits per five ton capacity
Hidden Cargo compartments: 400 credits per five ton capacity
Scanner Resistant Cargo compartments: 1,000 credits per ton of cargo capacity
Automatic Cargo Jettison: 1,000 credits
Tractor Beam: 8,000 credits
Passenger conversion: 400 credits per additional passenger added
Refrigeration Equipment: 100 credits per ton converted
Escape equipment: 1,200 credits per pod
Replacement Navigation Computer: 2,000 credits
Environmental Converters: 4,000 credits