Is it cheaper to purchase a mutual fund directly versus purchasing a fund through a bank investment service?

Answer 1

If you buy no load funds (they won't be available through a bank or investment service) you will pay less per dollar invested than if you buy load funds (which can be bought through banks and investment services).

Answer 2

Generally; if you use a discount brokerage like Fidelity and Vanguard, and you buy their own proprietary funds, it is much cheaper.

This is because thety do not have to pay for shelf space and distribution. These costs usually come up as front or back-end loads, and 12b-1 fees.