Service to be tested in Spain and Portugal this year, with a UK rollout if successful, as pre-loved markets boom Ikea is to test an online version of its buy-back service where the retailer offers vouchers for unwanted secondhand furniture. The service will be tested in Spain and Portugal before the end of December and will be launched in the UK if it proves successful. Ikea already offers buy-back in stores, including in the UK. The online version will extend it to a much wider audience, with Ikea predicting pre-owned goods are likely to grab 16% of the UK homewares market by next year…