I have attempted to purchase lenses somewhere in the 'middle ground'. I believe the very 'cream a-la cream' (top of the best) of lenses are often priced high, because of the laws of diminishing returns (with regard to image quality, etc). The 'cheapest / basic' lenses generally 'do things ok - but nothing very well. So the middle ground often works for me (both in terms of functionality, image quality and price).
Almost 10 years ago I bought my first Canon DSLR 350D, complete with the 18-55mm kit lens - but also had a few other lenses, eg the Canon 28-135mm and Canon 50mm f/1.8 Have since sold those 2 'extra' lenses (still have the kit lens). I used the Canon 28-135mm most the first few years, it was superior in image quality (and in many other ways- eg IS, USM, contrast, etc) to the 18-55mm - though of course 28mm on a 1.6x APS-C / crop body isn't very 'wide'.
Then upgraded to the Canon 7D, and have the following lenses (and I use all of these extensively):
Sigma 10-20mm f/4-5.6 HSM EX
Canon EF-S 15-85mm f/3.5-5.6 IS USM
Canon EF 100mm f/2.8 USM
Canon EF 70-300mm L f/4-5.6 IS USM
The only 'future' lens I'm looking for is a new Canon EF 50mm USM fast prime. (None of the current 50mm primes - either Canon or 3rd party) is really what I want.
I have upgraded a few lenses - eg Canon 100-300mm USM to the much better Canon 70-300mm L IS/USM, because eg the lack of IS AND the image quality at tele end just weren't good enough. In other instances I bought a 'totally new lens' ("new" in my line-up) - like the Canon 15-85mm which can't really be compared with either the 18-55mm kit lens nor the 28-135mm. Only the 17-85mm is really comparable - but it is not very good IQ at wide end.
The 17-55mm f/2.8 (better for low light- but not the zoom range I like). The Canon 100mm USM macro is another 'special purchase' lens, and one that I decided on after using a friend's copy of this lens, and I was 'sold' as in - what I wanted in a macro lens. BTW, I keep the 18-55mm kit lens as it's a handy light 'travel option' - eg going hiking with my 350D.
I have achieved thousands photos that I'm very happy with, and many people that I've shared these photos with really appreciate them too... so I explain I've got 'good camera bodies and lenses' - but not 'the best / professional' ones. It's more about technique, understanding light and being creative & composing well. I'm very happy with my kit, and as I wrote above, only see a 50mm prime as a future upgrade...hopefully Canon will release a great new (hopefully IS / full USM) prime in the near future.