There's nothing spinning in the rack, so I'd say your vibration is not rack related. Swap your wheels front to back and see if the vibration moves with the wheels. This will separate the vibration from wheel/tire and other drive train issues such as cv joints, etc.
If you do go for a rack, remember to have new hoses and a pump installed too. If you have a cooler, either make sure they flush it or get them to install a new one. Any contamination will destroy a new rack.
1500 for a new rack? Wow, I saved thousands doing my own work! I also changed my high pressure line, ball joints, pump. I can sure say I KNOW why they charge so much. It wasn't easy.