You should be able to do it yourself. I assume you are talking about the seals that seal the injectors into the inlet manifold?? If so they are easy just take your time with them and you should not have any problems. Have you got yourself a manual?? If not let me know and i can run you through it. To get someone else to do it should not cost you the earth though. It should only take a mechanic half an hour or so to do the job. I would not expect much more than 100-150 to get it done by a mechanic.
What's the difference between understeer and oversteer? Understeer is when the driver is scared. Oversteer is when the passenger is scared.
its fairly easy just remove the fuel regulator then remove the fuel rails. the injectors then simply pull off and you can clean them up and replace.... although id get them fully cleaned while their out just to make sure there in tip top shape