Hello and thanks for the responses! In order...
Stashasaurus- thanks for the advice, you gave me some good pointers I've added to the list. The fellow seems happy enough to have me check the phone out in detail so I figure it's probably good.
okobrien- I'm with you, I'd love a shiny, blingy new iphone/galaxy but it just doesn't make sense. This one seems like it will work well for several years and I don't need anything super fancy. I don't play games on it even. Since my old one was super-cheap and marginally functional this will be an amazing step up. I had to turn of javascript on my old one to keep it from crashing, which can make logging in at guest wifi a hassle.
I.P. Daley- I'm happy to replace the battery as necessary - my fujitsu laptop had the charging port die and I fixed that (involving soldering and lots of parts removal) so compared to that the battery swap looks easy. I'll take a good look at the screen and test all the ports.
acroy- It's a matter of supply. It may be different where you are, but if I buy a certified refurbished G4 the cost is $229 from canada computers, for a new G4 or used G4+ it's $300 , and for a new G4+ it's $400. Plus 15% tax. Prices on Amazon.ca are similar- to do better I'd have to do a remote used third party, which is much less trustworthy in my opinion. That makes a $200 used G4+ I can examine in detail before purchase look pretty good.
Current checklist;
sim cart port/unlocked
visible damage/scratches
IMEI (not stolen)
microSD card port
headphone jack
GPS
Touch-typing works well
text and calling ok.
Camera
Charges from laptop using cable, and connects
can access wifi