so what do i need witch is good but cheap

note its not the motor geting hot
can i get away with just buying the speedo or just the motor or will i need both has any one got a setup plz
note im just 14 and havnt got the money to buy these 400 pound cars

and 200 motor combos

plz dont give me a link to something that is silly money
butif u could help me id be very happy