Can anyone explain how to earn 1000 carnival shards without breaking the bank?

Its not. Buying players for exchange or spending huge amount of gems is the only way

It's pack luck based so if you are lucky and pack highly rated players, you won't break the bank, however, as Sanyo said without spending resources it's unlikely going to happen due to the construct of the game. If you want a player and you don't have enough gem,s then look at trying to snatch him from the market. Buying cheap cards (unless you are missing like 10 or 20 shards) is a very expensive way to get an untradeable card.

The other thing you need to consider that TOTY was 7 weeks long so you had plenty of time to collect the shards and cards for it. Carnival is 2 weeks so chances of getting those cards are minimal through usual game progression unless you start spending real money.

Thank everyone for providing valuable suggestions.

I have done all that with winter event and TOTY events, I acquired the cards I wanted with ease.

But this weird event is short and cards are rare and expensive, ex. the cheapest 98OVR card is near 100M. this is not a playable event. EA should stop coming up with this kind of garbage. 

It’s just a filler event - do the basics and move on …