Starting with the transformer if you go the linear route you are looking at about $30 USD, followed by about maybe $5 USD for a full wave bridge rectifier, followed by maybe another $5 USD for filter capacitors before we even worry about regulation. Then comes building or making a board to put the components on plus a box for the power supply to call home. Now I am not knocking home brew or the benifits of building a power supply yourself but given a choice why not consider finding a home computer ATX form factor power supply? For about $20 USD I can buy a plain Jane PSU that will deliver:
+3.3V@24A; +5V@30A; +12V1@12A; +12V2@13A; -12V@1.5A; +5VSB@2.5A.
Used units in scrap computers flood tree lawns in the US daily and can be had for free. Again, if there is a specific reason to build I can understand but for a quick and simple 5 volt 10 amp solution to drive a motor I would just find a cheap or free ATX PSU and use it. I doubt the motor will care and it is already in a nice little metal can all packaged.
Just My Take
Ron