I used to run computer PSU's when I had wipers, but they were spare PSU's I had. They originally only cost me $30 each.
However, the PSU's only really put out 18 amps at 12v. So I had one per motor. This worked ok, but they would still trip out from time to time.
Here in Australia, I decided to buy a proper benchtop power supply via ebay or when they are on special at radio ham shops and electronic shops.
That and I didnt have to chop up a perfectly good computer PSU.
The neater option is 2 power supplies.
The cheaper option is one power and one car battery in parallel.
Now with the big worm gear motors, I just run one 13.8v 32 amp power supply and one car battery rated at 405 CCA in parallel. Plenty of current for big spikes.
Floriske is on the right idea about 2 BIG power supplies for his big motors.