I need to start thinking a bit about what kinds of services are available in Wyndhaven. Iron Marches has a whole list of alchemical goods and arms & armor, including limited amounts of special materials that can change over time (for example, there is 12k gold pieces worth of adamantine available but it costs +15k gp to make adamantine heavy armor, so there is no way to get it without waiting for a shipment from the old world (probably need to put up a hefty down payment before such an order will be made) or you find raw material in the wilderness and get it back (to hell with you if you think they'll send someone to mine it)).
The specific idea that prompted this post was the use of horses in Iron Marches. Most of the characters have mounts to allow them to cover more ground outside the city walls (and the city walls are huge, cover 20 miles deep and 8 miles across).
Wyndhaven, while controlling a similarly large area, is not big with horses. Those steeds that are present in Wyndhaven are used almost exclusively by the garrison to patrol the wall and check on the farmlands. Some draft horses are probably also at those farms to do work. As such, there are not extra horses to go around for PCs to use. Either they will have to wait for a birth or a shipment or they will have to capture their own steeds. Stealing is also possible, I suppose.