No way should you pay $500 for an 83 550. The pre 91 550's all had cast iron cylinders and they are POS. 90% of my mechanical knowledge came from trying to keep those things running, and I know a lot! The problem with such an old ski is that when they break it will cost you twice as much as you can sell it for in a running condition just to fix it. If you do buy a 550, then don't touch anything that isn't a 550sx. The 550sx came out in 91 and had an aluminum cylinder with iron sleeves. They were way more reliable, and I wouldn't pay more than $400 for one of those. The BEST entry ski out there for a "new to the sport" rider is a Yamaha 650 Square nose Super Jet. They go for between $600-900 now. Pay the extra money, you'll be glad you did.