No one has actually answered your question. I did some calculations and the absolutely 'cheapest' you can get by with is the 150 Disney minimum purchase.
This will give you 8-days in an OKW studio in Adventure season for 88 points, leaving 62 points to rent out. Assuming you could rent them OK and get $10/point that would give you $620 rental. After paying income taxes on the rental income, you would be close to the approximately $600 annual fees for those points (Assuming you purchased at BCV. If you could find a 150 point OKW resale it would help as dues are lower).
150 points from Disney is $12,600. Annual fees are about $600 a year, or $50/month if you have the fees automatically deducted from your banking account.
Remember Adventure Season and OKW resort are the absolute minimums for DVC stays. Adventure season is January, September and the 1st two weeks of December. At OKW this is 8-points per night weekdays, and 20 points/night weekends.
From there everything just goes up. At the other WDW DVC resorts those same 8-days in Adventure season range from 94 pts (BWV Std-view) to 116 points for all the others.
Step up to a 1-B/R and the four resorts go to 176 to 222 points for the 8-night stay.
Keep a 1-B/R and go in Magic Season instead and the points range from 240 to 300 for the 8 days.
So the IF's: If the $12,600 only takes part of your money and still leaves a substantial amount left over for other bills.
If you can afford to pay the $600 annual dues without having to rely on renting points.
If you would be happy staying in the lowest season, in the lowest accommodation (Studio), at OKW resort.
Then...Maybe it's OK for you. Only you know your other expenses and incomes. This would be the bare minimum.
If you're looking at staying in a 1-B/R for 10 nights at BCV for example, in Magic season, it's 360 points, you'd need to purchase about 700 points ($58,800) in order to have 340 points to rent each year (at $10 each for $3400) in order to have enough after paying income taxes on the $3400 to have the $2800 annual dues payment. Keep in mind there are no guarantees you'll be able to rent points every year.
Keep in mind this only gets you a place to stay. As mentioned, going to WDW is expensive. You also need to include travel, meals, park tickets. These things can add up big time very quickly.
Think carefully and be sure it's the right decision for you.
As for advice, I'd say that if you forget about the money you received, and in your current financial situation you could afford to buy the 150 point minimum and safely make the $600 in annual dues, all on your own without having to rent, then do that. You can always add on later.
150 points will get you 9-days in a Studio at any resort (OKW, BWV, VWL, BCV) during Adventure, Choice, or Dream seasons (which covers about 60% of the year).