First off, I'm asking this because the NES isn't my favorite system and I'm satisfied playing the majority of the library via emulation and I don't wanna spend a couple hundred on an AVS

What would be the best hi def clone to buy to play the Nintendo World Championship and NES Campus Challenge repro carts? Are there any out there short of going high end with an AVS or Analogue NT that will play these without any issues?

Thanks   

If you just want something cheap and dirty get a retron hd. For the price, you can't beat it. It's not perfect, but as you've stated, your not willing to pay AVS prices.

Edit: I haven’t tried those repro carts in this system, so can’t say if they work

When you buy those clones, you are buying junk. They dont hold up to moderate heavy use. You get what you pay for.

But if you ARE willing to pay AVS prices.. you will not regret it one bit. Thing is awesome.

As the saying goes, you get what you pay for.  

The only two that might have a shot are the GamerzTek NES clone or the Retro-Bit Super Retro Trio.

But if you can swing an AVS, that's going to give you a lot more value for your money.