Handicraft prices in Tonga have increased in recent years but you can still find bargains if you shop around. Baskets, mats, and occasionally tapa are reasonable buys, and there's no hard sell anywhere, so you can browse at leisure.
A good place to begin is Langafonua, the Tongan Women's Association Handicraft Center on Taufa'ahau Road in the center of town. Friends Tourist Center sells quality handicrafts and books.
Also check upstairs at Talamahu Market, where you can buy directly from the craftspeople. Bargaining is possible but avoid buying anything at the market on a cruise-ship day when prices are jacked up.
A "lane" or langana of tapa at the market is more expensive if it bears a crown or Tongan seal designs. Tapa is best purchased directly from the producers—just listen for the sound of the beating while you're touring the island.
Several shops along Taufa'ahau Road sell fancy Tonga shirts, including Look Sharp Tonga and Blue Banana Studios.
The Philatelic Bureau, at the post office, sells attractive stamps and first-day covers from Tonga and Niuafo'ou.