Should you rent or buy noise meters?
This really comes down to how often you are thinking you will be using your noise meters. Here's a rough suggestion for how to work it out.
Have a ponder on how many days you think you will need to do decent noise measurements for your workplace.
Look at what the rental cost would be for that number of days.
Look at the purchase price of a decent hand held meter, calibrator and maybe three or four personal wearable meters (dosemeters).
Get a quote for how much it will be to have them all calibrated (every two years remember, it doesn't have to be every year).
Add up your purchase and calibration prices.
You will probably be looking at something like every three years to do a full noise assessment for your site.
Noise meters have a life-span of say 12 years, some more, some slightly less. Mostly because by then they may be working but are positively antiquated and things have moved on a long way.
For rentals therefore, you have that rental cost every three years, so over 12 years you have 4 x the rental cost. Compare that to the one-off purchase cost plus 6 x calibration costs (every two years for 12 years) and you have a good indication if buying or renting is better for you.
There is one big advantage to having purchased your own noise meters, and this is the ability to respond quickly to changes in the workplace with no additional costs. For example, if the production department introduce new machinery or maybe relocate existing machinery, built a wall, etc. you can quickly update your assessment with new measurements.
If the site changes hours of work and working patterns such as job rotation by the way, you do not need to actually measure the noise again. You could simply take the existing measurements and recalculate exposures for maybe prolonged exposures in one are and reduced exposures in another. That is a job that doesn't necessarily mean actually remeasuring.
If your site changes the facility around a lot then that is another factor in favour of buying, whereas if it is fairly static then the balance is more back to the middle.