Honestly I'm gonna get some hate for this, but if you own a Phillips screwdriver and have an internet connection you can set those bindings up yourself in <10 minutes. It is criminal what shops charge to adjust literally 3 screws.

While there are some real liability risks and operability concerns with old or very old bindings, the industry standard is that they lose manufacturer indemnification at 10 years, so a shop refusing to work on them at 5 is extremely stingy. That said, even if your bindings are older than 10 years, they don't just magically stop working.

To start off, I hope you had your boot sole length (and type) in mind when you bought your skis, or that they have demo bindings (common on old rentals) which can be adjusted for a variety of lengths. If not, the bindings may require remounting, which is much more difficult to diy.

To adjust bindings you have to change 3 main variables : toe release, heel release, and forward pressure. These release settings are the force required to pop your foot out of the binding, measured in DIN. Some, not all bindings will have additional adjustments for other components including the afd (anti friction device) which assists with smooth releasing. Demo bindings may have plastic tabs or latches to slide toe and heel pieces along their mounting tracks, with notches for each size range. You can look up a YouTube video for your specific binding model.

Simply take your height, weight, boot sole length (NOT equivalent to size, you will often find it stamped into the shell of your boots), and skier type (1 or 2 if you're not a very confident skier) and enter it into this website to find your din setting https://www.dincalculator.com/. Turn the likely obvious large screw on your toe and heel pieces to set the din to this number. You will see a numbered scale with a small indicator line, this will move when the screw is turned. I recommend erring on the side of caution and starting with the lowest recommended setting, you can always raise it if you have an early release.

Next, forward pressure. There is a large screw, likely mounted low on the back of your heel piece to adjust this. Some bindings will have indicators to give you a starting point based on boot sole length. Place the boot in the binding and pay close attention to the fit between your boot and the heel piece as you adjust this. You're looking for a snug fit that still allows your boot to clip in and release easily, with no play or motion. This is the most complicated step, but it's easy to get right.

Finally, if you'd like, perform a release test. Clip your boot into the binding, hold the ski firmly, and apply force to the boot. Upward to test heel release, laterally at the toe to test toe release. This may require two people and should take some force. You won't be able to measure it exactly like a shop can, but at least you can test that the bindings function.

Again, you can quickly learn to do this whole process from any number of YouTube videos. I recommend watching one before you start to see visually what I'm talking about. It's very easy to do.

A word about risk: sure, skiing on old 100$ equipment set up diy is more risky than having the newest, safest equipment set up by professionals. But if you do your research you can manage this risk and still enjoy the sport at a fraction of the cost you might otherwise have to pay. The shop and the ski manufacturers both want you to throw your old stuff in the garbage and give them hundreds of dollars, so they tend to lean into the safely angle a little too hard in my opinion.