Another GP100 owner here. I bought one back in the late 90's, when my local gun shop was having a "truckload o' Rugers" sale, and paid $329.00 for a blued model with a 4" barrel.
That thing was overweight, and had a bit of a gritty trigger, but it was as reliable and as durable as anything out there. Even though I'm more of a S&W 686 fan, I still must give the Ruger GP-100 a healthy respect, especially since you're going to be really hard-pressed to find anything better at the cost of a GP-100.
I would often times use this gun to train people how to fire their first centerfire handguns, if they weren't comfortable with a semiautomatic (normally my Glock 17 is used for that task, with my custom handloads). By using some lightly loaded .38 Special wadcutter rounds, and with the heft of this revolver, you had a very soft-shooting combination that was great for bringing along those who had previously only shot .22 LR's.