Is the violin easy to learn if you have past music experience?

Your past music experience will make the violin somewhat easier to learn; but only because you know how to read music. Piano, clarinet, and guitar are not similar to the violin technique-wise but it sounds like you have a knack for music so you may be able to learn quite quickly. It's true, the violin has no frets but again, you're past experience (especially with piano) will make intonation come more easily. About violins, as a beginner a machine made violin will be fine. Go to your local music store and get someone to play the violins for you to find one with a sound you like. If you decide to pursue violin you may want to eventually get a hand-made one. But $500 dollars should get you a decent machine made instrument. And wierd as it is, older violins tend to cost more unless they have been abused by the owner so get a new one. I don't how big you are but if your not big enough for a full size yet you might want to consider renting a violin for now :)