Hi Skip,
I got into this hobby a year or so ago. All my experience is with Heng Long tanks.
I started out with a Heng Long Panzer III that had very old electronics in it, and no smoke and no sound, for about $80. I just went looking on Amazon and ebay and could not find those anymore.
There are three kinds of radios out there, and if you are going to run multiple tanks simultaneously you will need to know about this.
With the earliest radio (what was in my PIII above), there is no replaceable crystal. You have 3 channels to choose from, A, B, and C. So you can run up to 3 tanks simultaneously if you put them on separate channels.
The next generation has a replaceable crystal on the tank and in the transmitter. You can swap these out to make sure tanks are on different freqs for co-play.
The latest generation are the 2.4 Ghz systems. They slave to their tank and there are no interference issues to worry about.
Another nice thing about the 2.4 Ghz systems is that you can control the sound volume and the smoke on/off from the transmitter, not on the tank manually. That is nice. I think the 2.4 systems also give you better speed control and better turning than previous generations.
So I recommend going with a 2.4 Ghz system. Most of the newer tanks seem to be.
The cheapest all-plastic tanks run about $120 - $200 or so.
https://www.amazon.com/German-Panthe...heng+long+tank
https://www.amazon.com/German-Tiger-...heng+long+tank
https://www.amazon.com/Remote-Contro...heng+long+tank
The all-plastic tanks generally come with plastic gears in their transmissions, and have built-in slip clutches to prevent stripping the gears. Heavier tanks, like the Jagdpanther, will bog in heavy grass and dirt and you will get clutch slippage and the tank won't go. So a metal transmission is superior. If you buy a tank with metal tracks and metal drive and idler wheels it usually comes with a metal transmission.
Lighter tanks like the Sherman seem to do fine with the plastic transmission and do not clutch-slip much.
Metal tracks hang more heavily along the wheels and look more realistic. Plus they are just cool.
A "problem" with the metal tracks and wheels is you will have to paint them to match as they come bare.
So, you can get a fun-running, all-plastic tank for casual play for less than $200. If you want to upgrade to metal tracks, drive/idler wheels, and transmission, then the tanks cost about $250+. I think the metal is worth it. I have an all-plastic Jagdpanther and a metal-upgrade Jagdpanther and I would hesitate to buy a non-metal-upgrade tank again.
A word on the Airsoft / IR stuff.
I bought the Airsoft because I thought it would be cool to have a tank that really shot. Let me tell you, the airsoft guns in these tanks are no joke. They will shoot through 3 pieces of computer paper with ease. They will probably injure an eye if you got shot in the eye. And they will absolutely blast pieces off of other tanks if you shoot them. So if you are planning Airsoft tank battles be aware you will be smashing up your $200 tank.
You can buy airsoft BBs either online or at sporting goods stores.
Heng Long as stepped out of the IR battle arena as far as I know - all their tanks are now Airsoft I think. And even if you find a Heng Long IR tank, they may not be compatible with the Tamiya stuff, but I'm not sure on that. If you are just fighting at home, get matching IR setups. If you are planning on going to tank battles, make sure you get something commonly compatible.
Also I find the Airsoft guns are fragile/flaky and prone to quit working.
The smoker units in Heng Long tanks are also very flaky and fragile and all of mine quit working in short order. There is a tutorial around here on how to rebuild them with a real resistor inside instead of the coiled wire but I have not tried it yet. I think I will instead buy a drop-in replacement smoker eventually.
I think the Heng Long tanks are a good bang for the buck, but you will probably spend money on them on top of what you pay plus you will be doing a lot of tweaking/fixing on them.
I take mine out about once a week and just drive over stuff in the back yard and shoot myself with Airsoft bbs.
Steve