72 MHz is fine. I fly it all the time without a problem. Yes it is yesterdays technology but the AMA still recognizes it and it is safe.
Because it it 'older', you can pick up transmitters for dirt cheap. RCers everywhere cannot even give them away typically. I do a ton of trading and I know this to be true.
I do recommend getting connected to a local club. They will be your best bet to get off on the right foot. Talk to lots of the members because you will get tons of different opinions. Unfortunately it is a characteristic of the hobby that everyone thinks their opinion is the only 'right' one. If you talk to several members you will find someone that you get along with. If they have been in the hobby a few years you have found gold.
Nowadays $100 will get you all you need if you look around or go to swap meets.