Trade limit - The RuneScape Wiki

The Trade limit is a mechanism in the trading system that prevented players from making trades considered to be too "unbalanced", that is, where one of the two players involved in the trade gave much more than they received according to the item's value in the Grand Exchange. This limit only affects new accounts that have never subscribed to a RuneScape membership in the past, and is limited to a 25k limit disparity between trade and Grand Exchange values. Jagex originally introduced it as part of measures to curb real world trading. As a side benefit, the trade limit also discouraged and mostly eliminated "hacking" other players' accounts. The Trade Limit now only affects accounts that have never subscribed before.

Community, RuneScape Wiki

Grand Exchange - The RuneScape Wiki

Money making guide, Old School RuneScape Wiki

Restrictions have been placed on all new f2p accounts. : r/W385

Bypass The Trade Limit in RS3 Using Grand Exchange

Worn Equipment - The RuneScape Wiki

Bank - The RuneScape Wiki

Grouping System - The RuneScape Wiki

Marketplace - The RuneScape Wiki

Free-to-play - The RuneScape Wiki

RuneScape Raises Max Cash Trade Limit and Adds a Number of 'Community Hitlist' Improvements

Wilderness Warbands, RuneScape Wiki

The Trader - The RuneScape Wiki