I can't speak for other teams, but I generally push for my team to invest in new products for a number of reasons...
- Often times, the newer (and more expensive product) will last much longer than we could with the cheaper one. Over the lifetime of the product it ends up costing less per year and per hour of use.
- Often times, the newer (and more expensive product) can do more tasks than the cheaper one, making it a better value overall. In the case of computers, cheap ones could make good back up driver stations, or we could get them nice laptops than can run CAD, labview, and adobe products for website design without bogging down. Same thing with tablets in regards to potential applications scouting, etc.
- In the case of electronics, battery life is super important for us. Buying new makes that a little less of a concern.
- Used and less expensive equipment can be harder to find matching sets. When we buy new, I can buy multiple of the same item which is much easier to maintain and store, and when they do get old they can be spare parts for each other. Also, I can buy one now and reasonably expect to be able to buy an identical one in a year.
- Our students are expected to take care of their belongings (and they generally do quite well), and in return we make sure they have access to quality resources. We don't ascribe to the theory of "buy cheap things because the kids will just abuse them anyway." We buy them nice things and then expect them to take good care of them.
There's exceptions of course (we urgently need something and just have to buy whatever we can afford or get donated most quickly, it's a low priority item in which none of the above matter, etc.) but most of the time we can take the time to get them the most valuable product rather than the least expensive one.