Can anyone tell me what can happen if i buy a puppy with a level bite..is this something that could potentially cost a lot of money in vet bills as he grows and is this hereditary? Thank you

How old is the puppy ? The bottom jaw continues to grow after the top jaw stops, so a puppy with a level bite at 8 weeks can end up undershot.

As long as a dog is not grossly under or overshot the bite has little affect on a puppy's health.

Depends what you want to do with your puppy. If you want to show your pup, an incorrect mouth should be penalized, but a dog that does agility, hoopers, flyball etc etc wouldn't be affected.

Not sure why you think an incorrect mouth would entail veterinary intervention & costs. KC rules you cannot show a dog that gas been operated on to change appearances until there is an underlying medical issue that requires it & of course you have to get KC permission before showing your dog in this scenario

Some breeds are required to have a level bite, but a puppy that has a level bite at 8 weeks is highly likely to end up being undershot as an adult. This shouldn't cause any issues for the dog, but it's almost certainly inherited and so the dog (if of a breed that should have a scissor bite) should never be bred from. There's no reason why it shouldn't be a perfectly happy pet though.