In accounting, assets are anything an entity has which has value. Cash is but one asset: equipment, land and prepaid bills are also valuable. Most players will want something other than money as an adventuring reward. Think on it – what are parties planning on doing with that money? Skipping the intermediary, they could instead be rewarded with rare items, reputation, contacts, land or labor.
Historical objects might entrance your players more than cargo holds full of just gems. No matter whether something is “only” a well-made sword or not, if it's unique and has history many players will perceive that as added value. This works best for people who are interested in the campaign's history and aren't focused exclusively on game mechanics.
Names may precede the party and that can provide value all their own. Eventually they shouldn't have to prove their mettle to urban locals: legends can and usually do spread. Reputation can provide fun leads as well, from quests to plot hooks to expensive gifts. Wealth of this nature works best for players who are either showy with their character's skills or for players who particularly enjoy NPC interactions.
Beyond reputation, great tasks can win powerful friends. That power may stem from influence, might or wealth. The party might always have a friendly inn to stay at on the Eastern coast of the continent, or they might be able to count on the aid of a wizard's cabal should they ever require any difficult-to-come-by information. Rewards of this nature are best received by “mastermind” players who like to have many different strengths at their disposal.
Especially if your campaign is low-wealth, tracts of land can make for an amazing reward. Players can build a base of operations (or have one built) and make their mark on the setting in that way. Parties could even become respected lords as they defend villages residing within their borders. If you go this route, it's definitely a wise idea to also make the acquisition of materials and labor imminent for the party. Acreage works well even for system-mechanics-oriented players, and especially well for any planners in the group.
Equipment and supplies should have a lower cost via either the reputation or ally options above, but parties could instead have access to a labor discount. Armor could cost less just because the blacksmith whose life they saved is willing to work for free for them. Hirelings might pledge their services, for a time at least, and travel with the party. Whichever route you like, try and make sure that value isn't just a number. Happy appraising!