Yeah you can do it yourself if you feel confident, but if your skis and bindings are older I would highly recommend taking it to a shop to get the bindings fitted and tested. Like I’d run mine through a machine to test the release values of the toe and heal to make sure the bindings release properly and that’s standard in the industry.
You’d be surprised how many bindings fail after several years...but again it’s all on the consumer and what they want to do. If you want to save $30 also factor in the cost of blowing out your knee/ACL or breaking your leg if the binding pre-releases too early, or it doesn’t release under torque when it should.
Ski resorts see it all the time, Dad tried to adjust the bindings for each kid but didn’t nail it and now Little Timmy is in crutches because Dad forgot to adjust the DIN and the skis didn’t release...and it turns out the bindings were cranked so much they wouldn’t have come off Timmy’s feet even if he got hit by a bus.
Another suggestion I’d have is never buy ski boots without trying them on. If you try them on somewhere and know it fits then buy it online cheaper, sure, but I personally would never just buy a pair without putting them on my foot.