OP you got a very solid deal, no doubt.
I really like my P-10c. Reliable gun, eats all kinds of ammo I've tried. Feels great in my hand.
+1 for the HBI Theta trigger. I installed the 3.5# striker spring that came with the HBI trigger kit and it still reliably ignites those harder Wolf/Tula primers. HBI kit is a decent use of $65 in my opinion
The stock trigger is pretty good though -- I would say shoot it and dry practice a bunch before considering the upgrade.
Some things I don't like
1) mag release button on mine is way too stiff which I think means I have one of the earliest gens. It has lightened up a little bit but not much
However ^^ this is supposedly not a problem on the newer generations of P-10's.
2) Magazines are a little expensive and sometimes hard to find. $30 a pop at a minimum and that's when they go on sale
Yes, the mags are generally $30 - $35. Just the price you have to pay. If your gun is older, the newer style mags still work in them (actually work better in mine as the older ones had a problem dropping free and the new ones work perfectly). If your mag release is the same on either side and smaller, it's an older, non-2.0 version. Running rounds through it will loosen it up. You're correct that the newest model (2.0) has a slightly larger mag release that is much easier to use. Not nearly as stiff or require the same break in period that the older version did. I've owned the 1.0, 1.5 and 2.0 versions and the newest version works the best for me.