This is a bit of a mix, I had a Gen3 Glock 19 slide so I bought a PSA Dagger fullsize lower and matched them up. basically a Gen3 G45. This one uses full 17 round G17 magazines but has the compact G19 slide. Shoots really well and accurate. The Dagger trigger is better than stock Glock trigger in my opinion. 

A good G19 Gen 3 slide is well over 350 dollars just for the slide, I would take 350 for this setup or may trade if you have something I want can send offers. But 350 seems fair. 

Sniper Green lower good looking firearm, with Austrian Gen3 G19 Upper