For a mechanic, with the right tools, it should be a 30 min per side job, with most time being for splitting the balljoint as you cannot say how easy/hard thats gonna be. The rest of the job is a cinch!

Now if you are talking about the tension struts (can't recall whether they call them upper or lower) and that 2.5 hrs includes changing the actual ball joint too (which is a separate part) then 2.5 hours is not unbelievable if its as badly corroded into the hub as some of them get and the hub needs to come off to get it out. Its still high for a 'book' time though, 2.5 would be a worst case scenario, not a norm.