Calle Sagarnaga runs uphill from Plaza San Francisco, and the higher you go the deeper into the market district you are. The lower blocks are artisan shops and the better souvenir operations: alpaca knitwear (sweaters, scarves, gloves, hats), silver jewellery, woven textiles from different regions of Bolivia and Peru, musical instruments including small charangos with armadillo-shell backs, and the usual range of tourist goods from the useful to the forgettable. Quality varies significantly between shops; it pays to compare before buying.
The street connects to the Mercado de las Brujas (Witches' Market) a few blocks up, where the goods shift from alpaca and silver to dried llama foetuses, herbs, amulets, and ritual supplies. Together, Sagarnaga and the Witches' Market form the main shopping corridor for travellers in La Paz, and they are genuinely interesting to walk even if you are not buying. The shops spill onto the pavement, the vendors are persistent but not aggressive, and the mix of things for sale — the entirely mundane alongside the ritually significant — reflects the layered reality of Aymara urban life in a way that a museum cannot quite replicate.