I have an old one,it is Great, plenty of shots, like over 80 on a fill, is accurate, nice enough balance.
When they first came on they were "all the rage" and many turned them into HPA.
After a while, I grow tired of the funky trigger and went online and found ways to make the trigger better.
The larger CO2cannisters are like $18 for two....that would be about and guessing close to 200 shots.
What I did is purchased a box load of those canisters for like $75,over 20, properly more,I forgot how many.
Bottom line I paid $220 maybe 10 years ago and put a long muzzle break on it , another $40-50 ,got a good Discovery scope on it,$120.
Worked the trigger,= a very good rifle now...
So you see the costs I paid ten years ago.
I like the Gamo Urban better,it is a PCP though, and needs to be pumped up and may cost a bit more money.....
If the 850 did not get so many shots with one CO2 canister I would not be happy....but it does.
All that said,it is worth getting for an easy-shooting rifle....if the cost of CO2 does not bother you.
BTW, Google it used to be a lot of info...