Not Glock, but SIG, same idea though. (this is what I did)
Wilson Combat P320 Carry with their action tune/trigger package, which is the grayguns trigger. On sale by happenstance $1250
Manual Safety added- bought the gun from them so they'd do it at the same time, also discounted $150
Different Iron sights- TFX truglo Pro times 2, xs big dots, xs R8 I think, and the like- over $600 with tool to install
Grip Modules - I've stayed ok cheap here, though that may change - $220' ish
Magnaported - $220
Parker Mountain Machine Barrel with their twin port compensator - $375
Different grip tapes - $30
DPM recoil system - $100
So, about $3k without taxes and feeling like I'm still forgetting things, and it doesn't even have an optic cut, which, for me, is perfect, but if you like optics, well, another several hundred comes out. Then you get into the mess of holsters and such.
However, is it worth it? I think so, this thing is absolutely sick at this point, it recoils like a toy, I hit better with it than I ever did with either of my other current guns with red dots, it's insanely fun to shoot, and I carry it because it's just "right." Though it's a big gun at this point. Jesus, don't forget an important point, it's reliable, hasn't had a misfeed or fail to eject or whatever, yet, 115gr - 147gr.
I built another P320, non-Wilson Combat, subcompact slide with PMM Barrel and micro comp, grayguns competition trigger again, manual safety added. Easier to carry, still not as flat or fun to shoot, but flat and fun. Just ordered a $160 adjustable rear sight from SIG, busted the screw off in it, so, just ordered another $160 adjustable rear sight from SIG, just like that $320 on a rear sight that's plain as plain gets but I have the optics plate with no dovetail... not much choice.
Point there, you can do better the second time around now knowing more of what works for you, but you still have to throw money at it at times.
I have a 2011, and it's nice, and I love 1911s, so it was the "dream," and I think it's going to get sold, these two P320s are just too good, and I always hated the idea of a striker fired handgun, I was against these from the drop, 2011 had an easy win.
P320s are simple as simple gets to work on though, and things work easily, they shoot very well, but a guy could get a 2011 with a comp or similar and it would shoot like a toy too, don't get me wrong I know that, but the finicky stuff is still there, mags, one works one doesn't, more difficult to take apart and work on, and so on.
So, I would start modifying the Glock, first thing I'd get for that thing is the Radian Ramjet and Afterburner barrel and compensator combo. I'd get a DPM recoil assembly to go along with it, if they make one for it, keep it reliable, then go from there.
Just don't be surprised if you end up liking things so much that you need to do them to everything else you have.