I decided to get into PCP last June and looked at the buy in - gun, scope, and air source. It was a little intimidating. First I bought a scope, then a 90 C.I. 4500 psi tank and then a Marauder in October. I liked it so much I bought a Talon in November. I soon realized that I was using a lot of air as I would shoot 2 times a week in my back yard = around a 120 pellets each time. There is a Sport Chalet about 15 miles from me so I have a source for air, but it is out of the way for my normal travels. So I bought a pump - that helps a lot. Now I'm planning to buy a bigger tank this year and another rifle, so I should be pretty well set up. If you figure that you shoot 1000 pellets for around $30 - $40 versus $300 - $500 or more for a 1,000 rounds of rifle ammo you can justify the investment in equipment. The only cheap rifle ammo is 22 and I don't have one. I probably spent over $1500 in 2015 on ammo. This year I've already ordered 500 rounds of 17 HMR and 600 rounds of 223 for a total of $380 shipped. This should last for most of the year as I'm shooting my PCP's more often. I just received 2000 pelllets from Pyramid for $50 shipped. Should last me for about 3 months.
I forgot to mention that when I bought my Talon, Air Gun Depot included the AF CO2 adapter and a 9 oz. CO2 bottle. I installed it and shot it today for the first time. You are supposed to get many more shots per bottle than with the standard pressurized air tank. Just another option.