Tripod Help Advice Needed - D7000

I would like some advice on selecting a first tripod that will serve me for a couple of years until I can afford one that will support a 550-600mm lens for my sports photography (for occasional use only)

I currently use a Nikon D7000 with an 18-250 Tamron.

I plan to add a Nikon 24-70 and 70-200mm.

I am figuring that I need one to support 10-11lbs.

I would also like to stay between $200-$300 if that is possible.

Your help is greatly appreciated.

Harry