Gas is cheaper in the long run if you fly a lot simply due to the cost of fuel. However, the initial cost is quite a bit more and they are more complex. Nitro is definitely the cheapest initially and I would recommend going fuel first to see if you like it, then move into gas.
My favorite plane for starting nitro is the Sig Kadet LT-40. It's a high wing trainer but it's plenty aerobatic and I still enjoy flying my brothers even though I'm advanced well past it's limits. It's just a fantastic plane. Sig offer very high quality kits and they include all the hardware so you aren't hunting for things after the fact. They also offer ARF's (almost ready to fly) and combos. If you get their engine (also good quality) then it's very inexpensive. If you are buying your own engine you can never go wrong with an O.S. engine. Their .46 is a perfect match for that plane. Magnum engines are cheaper and also very good.
This plane floats in the air so well that my brother has had some engine failures (old old old engine) and was always able to glide back to the strip and land safely. It seems to just hang in the air. Also flies inverted very well. Basic aerobatics are great with it.
http://www.sigmfg.com/cgi-bin/dpsmart.exe/IndexAircraftF.html?E+Sig
You can hand start models, but it's a pain and you need to have it warm and tuned first. I highly recommend getting a starter.
http://www.amainhobbies.com/product...ucts_id/37899/n/Hangar-9-PowerPro-12V-Starter
You'll need a fuel pump, I'd go with hand crank. At first you can just stick the hose in the jug and after a while you'll probably add fittings to the top so it's not so messy.
http://www.amainhobbies.com/product...ucts_id/207400/n/Hobbico-Hand-Crank-Fuel-Pump
Fittings for the jug cap
http://www.amainhobbies.com/product..._id/29357/n/Du-Bro-Kwik-Fill-Fuel-Can-Fitting
I highly recommend running an inline fuel filter
http://www.amainhobbies.com/product...roducts_id/74652/n/Du-Bro-In-Line-Fuel-Filter
You'll need a glow driver. Here's where you can go cheap and regret it or buy a nice one once. I went the cheap route twice and after doing a lot of research I bought a nice one and will never go back. Even the nice ones are pretty cheap. The big difference is whether or not it uses regular batteries or is rechargeable and the attachment type. I prefer the twist lock. I've had the least amount of trouble with twist lock. Most of us heli guys use twist lock because our glow plugs always mount on the side but after trying it with my planes I love it. Again I'll never go back.
Here's my groups favorite. As in we all use the same one after trying a bunch of others.
http://www.amainhobbies.com/product...d/14477/n/Hobbico-Super-Hot-Shot-5000mAh-NiCD
As for fuel, you'll have to run whatever your local shop uses. I have run Wildcat fuel and currently run Byrons (based only on availability), both with great results. I run a YS20 blend. The YS is for YS engines, they originally came up with the spec. The 20 is 20%nitro and 20% oil. It runs great in everything we fly. All our planes and helis use the same fuel with good results. My brothers entire club flies on YS20 blend fuel for all their models except some of the higher performance helis use 30% nitro heli blend.
You'll notice that I link AmainHobbies a lot. I love Amain, they've been fantastic to deal with, always ship quickly and almost always have free shipping. They also have a huge inventory and great customer service. I mean great customer service. They have an inventory comparable to Tower Hobbies but Amain has better shipping and more brands.
If you have a local shop I'd recommend going there and building a relationship with them because they'll really be the ones you turn to......if they're any good of course. Like I always recommend, find a local club field and if they have good people find a mentor or two. Nothing beats experience when learning, especially tuning engines.
If that's something you're interested in, the AMA website has a club locator.
http://www.modelaircraft.org/clubsearch.aspx
That should get you started, I'll post a couple other good planes to start with later.
If you have any more questions please let us know here or message me.