Looking for used motorcycle, along with that I have some concerns..?

I agree that an older BMW would be a good choice, however, you may not be able to find one for under $3000 that is in good shape with low mileage for resale. You also need to concern yourself with your riding ability. Do you have the experience to ride a sport bike or a big heavy cruiser? Pick something that is right for you to ride and worry about selling it when the time comes. Everything will sell it just depends on the price.