You did the exercise for a car; basically the exercise is the same to do to understand the difference in prize for different boat.
It is probably easier to do for a car since you know cars for so long.
When hunting for a boat, you fist look at the length. You also have to consider the beam. Larger the boat, higher the price. (more room inside and on deck)
Next consider various factors.
Material, wooden boat, aluminium, steel, fibreglass, composite?
Tankage for fuel
and water, enough for what I what to do?
Accomodations, roomy enough for the time to spend on?
Room for storage, food etc.. enough for the time of the travel in between lands?
Fridge, freezer large enough? Still good working?
Sails – still good or ready to be replaced?
strong enough for where I want to go?
Electronics – up-to-date, or need to be repaired/changed?
And so on
These factors have a high influence on the asking prize for boats of same size.
Also, brands have some reputations for building boat as light build boat or strong build boat. Therefore 2 bluewater boats will go offshore, but you will not sail and make the journey the same way.
Off course, this a main factor to see difference in prize.
If we take an example (not a boat comparison, just a very very high level to help you)
What between a Dufour 44 Atoll, a Beneteau 44 Oceanis and a 44 Vagabond.
Once on board of a Dufour 44 Atoll, you will see there is nothing inside. No wood, no cosmetics, no warm, no personality. That boat is an excellent boat. Build at first for sailing course at low cost with less maintenance to operate.
Once on board of a Beneteau 44 Oceanis, you will find more details, more attention to construction and a warm of nice feeling that can be a good home. At that point the price rises since there is lot of work to achieve this.
Once on board of a 44 Vagabond, you might be surprised by how the boat can be roomy. Everything, especially on deck, seems to be strong and be build for stay for long and very long passage. It is also a full keel boat, compare to a feel keel boat for the Beneteau and therefore the prize is higher.
3 same size boats. 3 very different boats.
The exercise will remain the same with different brand of boat regardless of the size.
You will find an interest to browse yachtworld.com to see what you can get for your budget. Keep in mind, lower the price when purchasing, higher the fees to make her ready to sail.
You also can ask a broker to assist you. In that case you should consider a budget that make sense to him. I will say 150K, what include the purchase of a 36-38 feet, from 1980 or so and cost for reparation and upgrade.
Hope this helps.