Safety gear - Snell/SFI vs FIA

Is it worth paying more for FIA rated driver safety gear?

I don't expect to do anything more serious than low budget endurance racing, but I don't know how different the standards are, and if the added cost really brings added safety.

Follow the safety rules of your organization. FIA seats and helmets are distinctly different, but for most things you're just paying extra for a holographic sticker. Pay attention to the individual ratings. There's multiple levels of fire-resistance.

For some items (seat belts for example), most organizations allow the use of fia items longer than sfi. 

Also, there are a bunch of fia standards and sfi standards.  Some of the lesser sfi standards mean you need to wear fire proof undergarments to be legal.

The higher the standard, usually, the lighter the weight, the more breathable, the more comfortable, and higher cost.

Try to get a nomex suit if you plan to do this for a few years.  Otherwise, you will be buying one a few years down the road anyway....

We use all FIA stuff for rally - because it's good for 5 years vs. 2 for SFI (on things like harnesses, HANS, etc).

Nomex clothing as long as it's certed and in good shape, you can use it for 50 years lol.