I am hoping someone can help guide me in a direction. So my 10 yr. old is out growing his mongoose kong 20" and wants to stay fat. Knowing the cost towards the next bike? What do I look at next? 24" Fat from a big box store? Are there brands like Salsa or Surly etc. that trade up as he grows? I definitely know I cannot afford to buy new bike as he grows to an adult large or XL. Does anyone know of some other brands to look at that are sub 500. Any guidance would be great. Has anyone gone through this, and what did you do? Frame swaps? If there is a thread out there going over this, please direct me there; I looked for a few hours but did not locate anything... Thanks...