12v Power Supply for WS2815

Hi,
I am new in this field and sorry if my question seems simple and obvious for you.

I recently have bout 5m WS2815 led strip and I have a question regarding the proper power supply. I would like to buy a 12V power supply. I want to spend about 10-15$.

I could find two options:
A) Buy a used PC power supply
B) Buy a new 12V power supply which looks like laptop charger.

My questions are:
1- Generally which one you recommend?
2- Since I do not have any experience, which points I should consider? (for example an extra resistor or ... is required)
3- I read some comments that the power supplies in the form of laptop charger do not last long. Considering the fact that with the same price maybe the quality of laptop form power supplies may be lower, which type of power supply do you suggest?
4- Are the both type safe for a beginner?

Thank you very much.
Eliesi

My recommendation is to purchase a new one with some extra current capacity, it will cost a little more but it is a known good item. The extra capacity will help it live longer and run cooler. I see no reason for an extra resistor. Good Luck and have fun!