Heya fella sounds a frustrating issue.

The problem is it could be one thing or many in combination.

Are you running standard suspension/wheels/tyres and when did the issue begin?
I'd start with the obvious.

.

.

play with tyre pressures

(a bit less in the fronts compared to the rears than you currently have) and see what difference it makes.

The fact that you reckon the wheel vibrates strongly suggests an imbalance whatever the garage may say so try another set of front wheels known to run true at those speeds.

Check front brakes for binding.

Check wheel bearings are not on the way out

(Trevor at TCB parts has very reasonable replacements).

Bottom line though is it could be a combo of a a failing strut, old perished rubber bushes, worn steering components or any other number of things.

If it were me I'd check all I can myself

(swap wheels etc with another member) then if no joy take it to a geometry/steering/set up specialist like Wheels In Motion or a 2 specialist like Rogue and ask them to diagnose without fixing.

Once you know the issue the cost to fix should become apparent.

I hope you get it sorted because I know how much these types of issues, those that spoil the actual driving of the car, can colour your view of the vehicle.

Good luck

R.
