Fish
I set out to make the cheapest ship possible, you could consider this a scout. The total cost was $28,350
Costs:
Reactor - $15,000
Control Room - $10,000
Crew Bunk - $250
Crew x2 - $2000
Small Thruster - $500
You could always cut down on one crew member and then it would be a $1000 cheaper.
This has no weapons and is highly exposed and could only be used as a very safe scout. Finding the enemy identifying what it is and running.
Here is a image of what I created
TRASH YARD
Mass = 11,0 tons.
Cost = $28,350