Hi does anyone know why the huge price difference in Moki engines.Horizen Hobbies has the 2.1@$423,the 1.8@391 and the1.35@$359.Chief Aircraft has the 2.1@299,the 1.8@$289 and the 1.35@$239,Are they the same engines and if so why the wide range of price.I was in the process of buying a used 1.8 for @300 I thought it was a good buy because the seller gave me the Horizen website to check the price but now I don't know if I should buy it as I can buy a brand new 1.8 for @289 with warranty if it is the same motor. :