So I got hooked into Pathfinder pretty quick with some friends, playing Rise of the Rune Lords and are still only 2/3 through, and I have already got ambitious enough to get my kids going in Dragon's Demand and taking on my first GM.
They have all got about 2000 gp and I don't see anything in Belhaim where they can shop for armor or wondrous items, nor do I see the adventure taking them out of Belhaim at any time. Where are they supposed to buy some goodies? Should I just home-brew a shop or two?
The Belhaim appendix doesn't have a ton of info on the town, but it does list some magic items for sale and where they are at the end of the town stat block on pg. 56.
This at least gives you the names of a few places magic items can be bough and sold: House of Abadar, Shrine of the Seven Roses, Sensina Hides, Delbin's Devices and Chance Smithy. The table on page 61 lists a bunch of other locations and a bit about their inhabitants and you could flesh those out for your use as well.
When I ran it, I let the players travel to Cassomir between clearing Hunclay's Manor and the auction and buy anything they could afford.