Reynolds Emperor

Well I can see that these people are on the right track but here are some things you should know for this situation:
Repairing the trumpet: It's going to need a repair if it isn't playing right and the director likes to have his/her horns nice and tidy. $100 is a little overestimate for that though. It really just depends on who you take it to. My guess would be anywhere from $50-100. I would see if your band director has a repairman for the school before you take it though. If it is a school-rented instrument normally part of the fee money used goes towards repairs so you personally don't have to take it to a shop. It would save you some money.

Getting your own Trumpet- If you are going to take music through at least college and or the repairs are not covered by your school I would highly suggest getting your own horn. You can usually get a student trumpet for about $100-200 on Ebay or your local Craigslist. Just when you buy it make sure it is in fair condition and not to old. Normally people who sell them are people who have kids who wanted to try it but then gave up. So you can normally get some really good deals for trumpets.
Hope this helped at the least!