I play a yamaha tenor sax and i am about to go into high school next fall and I was thinking if it is a good idea to upgrade to an intermediate sax?

If your into playing and are willing to keep playing than yeah I would, try this site here http://www.wwbw.com/Tenor-Saxophones-Intermediate-Tenor-Saxophones-d2788.music these are the intermidete section I `d recomend the selmer TS200 or YAMAHA YTS475

All I can say is I played a YTS-23 for the longest time (the beginner) and now for christmas I recieved a YTS_475 and its the best thing to happen to my music.

You can get the pro model Yamaha YTS-62 or Selmer Mark VII, used, for $ 1500-$2000 if you are not concerned with the cosmetics.