Using quality gaskets and seals will help protect the engine and carburettor/s against unwanted leaks of oil, air, or water. Whatever the gasket's job, it will do it better if it is a correct specification gasket.
As with most things in life you get what you pay for, and using cheap alternative gaskets and seals could end up costing an awful lot more if they fail to do their job.
Using cheaper parts could be very costly! Add all the parts required into the same shopping cart - avoid multiple shipping costs.