I buy/bought my shredders at our local church charity Thrift Shop. I paid less than $5.00 per shredder. Over the past 4 years, I picked up 4 good used paper shredders from the Thrift Shop. None of them have broken yet, but if they do, I have extras. My used shredders have been in service for almost 4 years now and they are still working great.
My tips to prolonging the life of these shredders are:
1) know the sheet limit for the shredder and stay under that,
2) shredding a little paper each day is better than overworking and overheating the shredder on a massive shredding operation. My shredders have a maximum run time of less than 10 minutes before you have to let them cool down. If I shred the paper every day as I get it, I only am shredding paper for maybe a minute or two at the most.
3) if you shred cardboard, cut it into narrower strips to fit down the "credit card" if the shredder has one. I cut my heavy cardboard into about 2 inch wide strips and feed it down the center of the 10-sheet shredder.
4) don't shred any cardboard if your shredder cannot shred credit cards because it could jam the motor and burn it out or break the gears in the shredder rolls.
5) Clean out the bin frequently. Paper shreds can fill up the bin fast and prevent the new paper from flowing into the bin correctly. This can cause jamming, which could lead to overheating of the motor or breaking the plastic gears.
6) Newspaper can be shredded if you alternate it with regular paper or light food box cardboard to clean the rollers. The problem with newspaper is that it so very soft that it tends to re-roll up on the rollers and can cause a jam. So, if you shred newspapers, just shred a little newspaper and then a couple of sheets or regular paper to clean the rollers. You have to experiment with your shredder to see what works best.
7) You might be able to disassemble a shredder, clean it out, and put it back into service. I had one shredder that jammed up bad on something and would not work. Easy to toss it out since I only paid $3.00 for it, but I decided to take it apart to see what was wrong. There were some paper bits that had jammed hard between the rollers. I removed them with a needle nose pliers, put everything back together again, and it has been working fine for over a year.
8) Listen to the motor on the shredder. If you hear it bogging down, hit that reverse switch to clear it out, then refeed maybe only half the amount of paper that was causing the problem. A lighter load is much easier on the shredder.
9) Oil your shredder every once in a while to keep it in good working condition. You don't have to buy expensive shredder oil. Any vegetable-based oil should work fine. Don't use WD-40 or other aerosol oils to lubricate your shredder as they can be a fire hazard.
I don't oil my shredder very often, maybe only once or twice a year. But I don't run lots of paper through it like a business would. Also, these companies want to sell you their shredder oil so of course they recommend a much higher use of frequency than I suspect is really needed.
10) If you can find a good used shredder, you can save lots of money. I got a couple $100 shredders brand new for about $3-$4 each used and they have worked fine for over 2+ years now, that is a big savings.
Well, those are some tips that come to mind off the top of my head. I shred almost all my paper products at home and use the free paper shreds as deep bedding coop litter for my chickens. When I clean out the coop twice a year, the old paper shreds are dumped into the chicken run composting system to make compost for my food gardens. Better to reuse that paper as coop litter then hauling off all that paper to a "recycle center" where I suspect the paper just ends up in a landfill somewhere.