Costco has the Delonghi Pinguino 12,500 BTU portable A/C for $389-$50 instant rebate= $339 + tax
This unit gets good reviews and has worked great for me for the last 3 months, cooling a medium sized room (16x14ft). Some of the older reviews talk about some issues with the units clogging, but it seems like these have been addressed in the newer model, according to other reviewers and my experience.
I got it when it was at regular price. Went to costco today and bought it, then returned it with the old receipt.
This deal is published in Costco booklet but does not require you to bring coupon, instant rebate is applied automatically.
Not only is a great price IMO, but is covered under Costco's lifetime return policy.
This item is not in their website, B&M only.