re: Setting up automatic investing contributions in trading account

Robo-advisor services are the new thing. Dollar cost averaging and rebalancing means muted performance until the investment base is large enough.

Most brokers have the robo-advisors now. Most brokers do have some sort of automated investing service.

Vanguard has it (since you mentioned low-cost is a driving decision for you).

If you're already a Schwab client, check out Schwab’s Automatic Investment Plan (it appears that it may be mutual fund only).

What is AIP?

Schwab’s Automatic Investment Plan (AIP) is a service that serves as a dollar-cost averaging program* allowing you to invest a fixed dollar amount at regular intervals in an eligible mutual fund held in your account. There is no charge for this service.

What funds are eligible for AIP?

All funds that are part of Schwab’s Mutual Fund OneSource® service and certain other funds are eligible. You must have an initial position in an eligible fund prior to enrolling in AIP.

What is the minimum amount required to start AIP?

Once you have an initial position in an eligible mutual fund, you may invest as little as $100 per fund per transaction.

How often can I invest?

You determine the schedule—twice monthly, monthly or quarterly. Quarterly investments take place during the first month of each quarter (January, April, July and October).