It would propably be cheap, If you use PC Power supplies. (ATX) They handle the current. How to get 24V? Well, you have to put them in series. This is definitely possible, but will be not easy and not safe, if the unit fails, because you have to set the mains ground 12V higher, because Ground ist overall Mains ground in those supplies. Play safe only! Do it, if you know about such things. A PC Supply is cheap, no more than 20$ - total of 40$. But you know, what I told you about safety with "floating" Earth Grounds.
Good luck.