What do i need to get started?

Here is all the goodies! The rifle and pellets. Depending on what kind of rifle .....little air compressor, air pump and filters for pump.

Yep, sell the tuck. and still put money away for the addiction.
Rifle
Pellets
Scope
Mounts
Bipod and Rail or shooting bags for precision shooting and sighting
4500 PSI tank to fill. You can use a hand pump but it will kill you. Tank is awesome. Check for scuba shops to fill tank
Compressor in the future, compressors are the shiznitt but expensive
Targets for sighting or print target from our target shooting section

Once you get it all set up and shooting good, THAT is when you need to buy another one in a different caliber.

I've been looking at this same path. Right now I've been checking where to get tanks filled and what tanks I want and how many.(fire stations, dive shops, and welding supply shops). I know how this will go with me and at some point I will get a compressor. But not something you have to start with. No way am I going to use a pump that would take out too much of the fun for me. Not going to sell a truck but will still be spending a chunk of change.

Since you know the rifle you want? If you are buying new the dealer can tell you what you will need to hook up to your air source. So if you want it all at the same time? You need to first decide how you will fill your rifle tank. The other items that you will pick up too support the air gun fever isn't a big deal. Just figure a dozen brands ands weights of pellets. And don't forget the scope and if you buy cheap to start with figure two scopes?

And never come back and look at this site again. If you do then you will need pellet sizers, pellet scales, camera mounts + a camera,range bag, the book on air gun laws in your area, and a second truck to sell for all the other good stuff you will think you can not live without? Don't you just love the world of air guns?

P.S. go ahead and make a youtube acct for that camera footage you are going to create?

I think all that other stuff is overkill in my opinion...unless you're striving to be an olympic marksman. I don't have time to wash and lube pellets, measure the head sizes, sort the pellets by weight, calculate the gravitational effect of the moon, track the ISS orbit, etc...

My list:

1) Gun
2) Pump/scba tank
3) Pellets
4) Scope
5) Targets
6) Time

I've got everything on my list but #6. Between ice hockey and and scouts for the boy and hockey for me, I don't get much free time.

I got started about 1 year ago with a marauder. It was a great gun. My biggest asset there is a paintball place near me and they fill my tank for 3 bucks and a lot of times free. I probably wouldn't be able to afford my next step if I had to buy a compressor. I have moved up to a FX impact and sold the marauder. The versitility was important to me. I am not selling trucks but I am selling powder burners to feed my addiction. I love to squeeze a trigger and I can do it in my backyard with air. The ability to change bottles and have 2 extra bottles for 500 bucks over 800 dollars for a big tank that you can't carry while hunting. More companies are coming out with the ability to change out your air supply. I have a 90 cubic inch ninja bottle and I am considering selling it to buy another bottle for the impact. Mobility is very important the more I shoot. Having your own compressor doesnt solve the problem of mobility. More companies are coming out with guns that are more versitility. How you are going to get your air is huge. Having to buy a compressor and extra bottles would have been a deal breaker for me. I think right now is a great time to get into air guns. The technology has taken a huge leap in the last year and companies are listening to the consumer and giving them what they want. The government hasn't regulated the power or noise suppression yet. 

The tank is usually the biggest $$$ hurtle when getting started. I’d recommend keeping an eye on the classifieds for used tank. You might also consider a guppy tank. It’s a lot smaller and therefore less expensive but more refilling. It’s all a give and take no matter how you shake it. A hand pump is the least expensive way to get started and, if nothing else, will really motivate you to get a tank system ASAP (especially filling to 3000). If you can swing a tank setup right off the bat make sure you have a way to fill it already figured out. Staring at empty rifles and tanks is just poopy! Other than that, I’d say the same as everyone else…
Rifle
Scope & mounts
Pellets
Filling system
Targets 
Time
You can skip the bipod by using a rolled up jacket, sandbag, etc. If you go for a bipod then you might consider having your retailer install the stud or rail. If they mess it up it’s on them. Welcome to the dark side, you’re going to love it here! 
Tom

See if you can find someone who does Hydro testing on tanks-in my area there's a guy who does hydros and fills and he usually has used scuba and carbon fiber tanks for sale. I shoot 2 Marauders (tuned for low pressure fills) and a CZ 200 that all use 2500 psi or less as working pressure and use 3300 psi scuba tanks to fill. I shoot a fair amount and it still is about 6 months between trips to the fill station.
Good luck,
John

Pumping really isn't too bad if needed, if your healthy and use proper technique a pump might just serve you well. 

John