Don't know what carbs you have.
It's a pretty easy DIY thing on pre emmision Strombergs (don't know about others) as long as the bodies aren't worn where the spindles go through). The only fiddley bit as I remember is separating the connecting rod ball joint things (tapping out one of the rolled steel pins). Not sure if the ball joints are available new, if yours are shot.
Buck Eye Triumph have in depth re build info, on the net.
If you don't want to DIY, then carb specialists will re build, maybe cheaper than that E bay price (I would imagine they are refurbs).