Tripods that are very "portable" (ie light...) tend not to be very "sturdy". That's just the way it is. The tripod's own weight adds rigidity; fewer leg extensions = more steady.
I've got an ancient Manfrotto tripod for when I'm close to home (or close to the car). I bought a terrific 'one-touch' head for it: pull a kind of long trigger to compose the shot, and let the trigger go to lock everything up tight. Result: no camera shake at all...
For trekking over the hills I have a smaller, lighter tripod that attaches to my shoulder-bag with straps. It's a compromise: in breezy weather not every shot will be pin-sharp (so I shoot a few frames to cover myself).
Instead of seeing a tripod as an inconvenience, I try to see it as 'freeing up' my photography. I love to keep photographing after the sun's gone down, and I don't want to change the ISO from 100... so my tripod actually offers me more options than any new lens I might buy.
No need to buy new; tripods are fine to buy second-hand. Take your camera along and see how the camera/tripod combination feels to you...
also, what are you shooting? I am not sure this is your case, but alot of people shoot pass the monopod idea without a 2nd thought and skip right to tri-pod. Take a look at what your shooting and see if maybe you can get by with a mono. Could save you some weight.
The above really works. You can have any combination of two you want. But a good tripod will literally last you the rest of your life and then someone else will get to use it. So you can justify spending some money on it. You will buy five more cameras before the tripod needs replacing so even an expensive one is not when you look at the years of use you get out of it.
A steel Gitzo is likely good enough. But I'm not a fan of Gitzo's heads. Get a Bogen pan tilt head and Gitzo legs.
One trick. You can make a light tripod more sturdy of you suspend a weight between the legs. A water jug works good or a rock in a plastic bag. It tends to mash the legs down and makes it shake a little less