I own 5 springers, 4 of them being GAMO and 1 being an RWS 350. The GAMO guns are a .177 Shadow, .177 CFX, .22 Black Shadow and a .22 1250. My guns are completely stock, except for 2 of them that have Charlies GRT triggers in them (the other 2 will get the same triggers soon), but other than that they are just as I received them out of the box, and they shoot fine for me. Don't get me wrong, I know they would shoot better if they were tuned, but right now I don't have the money to get them tuned and I don't know how to do it myself, so I use them as they are and I more than happy with them. They are accurate, powerful, and serve me very well in my hunting trips.
I may get the rifles tuned someday, and I'm hoping that in time I will learn enough to perhaps be able to do some home tuning on my rifles myself, but in the meantime they perform well for me and do what I ask of them. It's also nice to know that if I decide to get them tuned, or need parts or advice, the resources are right here.
I'm not trying to swing you towards buying a GAMO. What you buy is a personal decision and only you know what's best for you. My moral was simply that you can enjoy great shooting with an affordable stock springer, whatever brand you buy, and later on if you want to "upgrade" it you can always do that. Anyway, good luck with whatever you buy.
JEff