Aestas has nearly as many forms of coinage as it does kingdoms. Most coins are roughly similar in size and value, assuming 50 standard coins per pound, while pennies vary wildly in size and composition - all are small. These currencies have been closely aligned over the ages by a combination of historical factors, convenience, coincidence, and the use of magic to assure purity and consistency. Use the chart below for flavor for the major currencies in use in the Known World. There are countless other coins and currencies in use, but these major ones can generally be used anywhere successfully, with little loss of value. Larger denominations are of course possible, but these are the most common sorts of coins. Most of the time, it is unnecessary to specify which specific coins are being used. Aestas uses the standard exchange rates given in the 5ed PHB, p143.
This article focuses on equipment of interest to adventurers, warriors, and other heroic types. Equipment prices and descriptions are primarily from the PHB. Most common technology found on Aestas is "high medieval" in nature, though many items from earlier stages of development are still in common manufacture and use throughout the known world. Truly primitive gear is often so rustic and primitive that it can sometimes be had for a fraction of the list cost, except in the case of armor. Fabric and leather remain in common use for light armor in most of the Known World, as both are ubiquitous and inexpensive. The most frequently encountered metal armor is mail (or "chain mail" as it is sometimes called); despite being laborious to produce, it remains relatively common due to economies of scale and cheap metallurgy. "State of the Art" technology is described "Renaissance", and is somewhat limited in availability. They can usually only be found in major urban areas, trading or manufacturing centers, or in the hands of the wealthy and well-connected. This is especially true of things like plate armor and black-powder firearms. Plate armor is not particularly rare, but it is expensive; possession of a full suit of plate armor indicates that the wearer is a person of status and means. Black powder firearms are only manufactured in a few specific cities, and their place of origin can often be determined on sight by the knowledgeable. Most of these guns are matchlocks, though a few are wheel locks; flintlocks are not yet in existence.Any of the options for weapons, armor, and shields are acceptable. Most all enchantments and magic items are not normally available off-the-shelf, as they are produced by artisans and are unique creations - though exceptions do exist. Most major cities will have at least one place that sells concoctions, potions, and poisons... though they are often more expensive than list-price. It is a seller's market, after all.
As an additional resource, it is strongly suggested that one should consult the excellent "Marketplace", by Mike Cubbin. This unofficial play aid is a comprehensive guide to prices for most of the things an adventurer might want. The supplement is intended for the author's personal RPG setting, but the shared assumptions are quite similar to those in Aestas. It can be safely consulted for anything other than armor and weapons, which are both discussed above. This rather large file is available in PDF form at the link below, and well as via Google. Though intended for use with GURPS, it can be consulted for ideas, and conversions are relatively simple, if you consider that one silver piece is a typical daily wage for a laborer.
"Marketplace", A GURPS Play Aid by Mike Cubbin (4.36MB, PDF)