Before purchasing the Yamaha TTR 125 dirt bike, do some research about the bike's features and specifications. Most importantly, you have to know what exactly you are looking for. Start by defining your budget, which will determine whether you get a new or second-hand bike.
Visit your local dealer and check out what they have. Compare prices with other sellers such as online dealers so that you get a good deal. If you decide to buy a second-hand Yamaha TTR bike, get more information about the bike from the seller, and, if necessary, let a professional assess and evaluate it. Negotiate the price and fill in all the paper work where necessary.