Doing it yourself is fine, provide you have three things: the little $5 hex tool, some blue loctite, and the $150 Glock sight pusher for the rear sight.
This is if you are installing Trijicon (recommended) or some other sight that uses the hex nut for the front sight. If you are talking about installing "factory" GLOCK night sights, then you need to have someone who (a) has the Glock "staking tool", (b) some epoxy, (c) really knows what they are doing.
I am not a fan of the staked front sight, having had them in the past. They always eventually come loose no matter what you do. The Trijicon ones are the best in that, if it comes loose (which it eventually will), you just unscrew it, re-blue loctite it, tighten it up with the hex tool and let it sit for a bit - and you are back in business for another year or two.
The rear sight is very straightforward, if you use the Glock sight pusher. I have one and could do it for you in 5 minutes if you were in Vancouver. Any shop that sells Glocks that is worth their salt should have one, but probably most don't.
So, phone around... you will probably get a lot of people on the other end of the phone that don't know much beyond how to take the magazine out of a GLOCK 17, and maybe field strip it, but of course they will be convinced that they know more than you. You will NEED the staking tool for the front sight on GLOCK factory night sights, and it should also be epoxied. You will NEED the sight pusher for the rear sight no matter what. Do not let anyone hit your GLOCK or your night sights with a brass punch and a hammer. Sure it CAN be done, but it is just so utterly primitive - once you have seen sights installed with a sight pusher - there is just no need for that.
I got tired of asking other people, so I got my own hex tool, blue loctite and sight pusher. That is probably the best overall plan if you are planning to shoot GLOCKs for an extended period of time.