Updating this in case it's useful for anyone...Casa Espacao opposite the Forum in Faro really wasn't bad. Good value and a decent range. Ikea type prices.
If you want swank, there's a gorgeous interiors shop in Almancil called Alquatro (same building as Casa Vostra which is a fab Italian restaurant). It's not cheap but for the items they have and quality/ style it isn't hideous either.