Non-elite members are limited to this type of upgrading as their only choice. The only way to upgrade to the front of the plane if you don't have elite status is to use AAdvantage miles.
Upgrades using AAdvantage points may be available for tickets purchased with cash (as opposed to award tickets). You could have to pay for an upgrade in both miles and cash, depending on the fare class. For instance, if you purchased a domestic discount economy ticket, you would have to pay 15,000 miles plus $75 to upgrade to the next level of service. However, you would only need 5,000 miles and no copay if you had purchased a full-fare economy ticket for that domestic flight.
To better understand the price to upgrade based on your original ticket, take a closer look at this American Airlines award upgrade table.
The copay and/or number of miles you'll need will also depend on where you're flying, in addition to the fare class of your ticket. Up to three flight segments in one direction are eligible for an upgrade.
By phoning American Airlines Reservations, you can request an upgrade at the time of booking or at any time before check-in, but there's no guarantee you'll obtain one under American Airlines Seat Upgrade Policy.
You are added to a wait list if the airline is unable to confirm that you will receive the upgrade at the time you request it. When you check in for your flight, you'll automatically be added to the upgrade standby list if your upgrade hasn't been confirmed by then.
It's not strictly first come, first served on the wait list. Your request for an upgrade will be prioritized by the airline in relation to those of other passengers (more on this later).