Overstock offers the Therma Spa 4-Person Inflatable Portable Hot Tub Spa, model no. EST5868, for $493.99 plus $2.95 for shipping. That's tied with our mention from last week as the lowest total price we could find by $52, although we saw it for $3 less two weeks ago (since expired). It features 130 air jets, a 900-watt thermostat that heats the water up to 104°F, zippered thermal cover, filtration pump, and two filter cartridges.