Target offers the Intex PureSpa Inflatable Spa, model no. 28403E, for $349. Coupon code "TGTST8DR" cuts it to $344. With free shipping, that's $6 under our mention from two weeks ago and the lowest total price we've seen. (It's also a current low by $26.) It measures 58"/75" inner/outer diameter and 28" high, seats up to four people, and features a 68° to 104° water temperature range, 120 bubble jets, insulated cover, heating system, hard water treatment system, filtration system, floating chlorine dispenser, test strips, thermal ground cloth, inflation hose, and carry bag.
Update: Specs corrected.