Kashgar has been a trading city for two thousand years and the tradition of goods from across Central Asia passing through here continues, at least in spirit. The best things to buy are handmade items with a genuine local provenance: embroidered doppa skullcaps, hand-forged knives with carved bone handles, silk ikat cloth by the metre, and dried fruit and nuts from the oasis farms.
The covered bazaar around the Id Kah Mosque is the main shopping area. The tourist-facing stalls closest to the mosque sell mass-produced souvenirs; walk a few lanes further back and you find the craftsmen's workshops where the real goods are made and sold. Prices are negotiable everywhere. The Sunday market is worth visiting for its general goods section as well as the livestock — you can buy tools, household items, spices, and textiles alongside the animals.
For practical items, the New City (Han quarter) has pharmacies, supermarkets, and hardware stores. The Bank of China and several other banks have ATMs that accept international cards, though it is worth carrying cash as a backup.