Sometimes a good cleaning will remedy your problem. If you do it yourself you can save some cash. If that doesn't fix your problem it is likely one of two things. Either the motor that spins the disc is bad or going bad. Or the laser assembly will need to be replaced. Neither of which should cost more than $150 to replace with labor costs. There are rare occations where the laser assembly is very expensive.
Pioneer's warranty on DVD players is 90 days labor and a Year on parts. So you may only need to pay for labor.