You neither have legal nor practical recourse in this instance for what you are hoping for. When it comes to lawsuits for "specific performance" (meaning, instead of money damages, the plaintiff wants the service or item contracted for), the "item" must be unique. By unique, think one of kind art work, real estate etc. As a practical matter, if Sears sold the oven, there is no way you can get "that" oven. And an oven is not going to fall into the category of unique.
If you sued, the most you can hope to get is the benefit of the bargain damages. Sears if offering to give you your money back (which you should take) and you might be able to sue for the difference if you have to go out and pay more for the same item. For example, if Sears' oven cost you $3500, and you had to go out and buy another refurbished double convection oven for $4,000, you might be able to hold Sears liable for the $500 difference.
However, Sears will likely defend that 5 months is an unreasonable amount of time to hold an item. And candidly, I tend to agree, it is one thing to expect a retailer to hold a big ticket item for a few weeks for pick up, but 5 months?
I agree with Mr. Berkus. You don't have a likely remedy here. If they sold the oven they can't give it to you. It isn't the fault of the people who bought it, and they've likely installed it in their home. You definitely should take the money Sears is offering to return.
Check your receipt carefully. Most retailers include a pickup date on their receipt. If Sears had a date on their receipt, they expected you to pick it up by that date. Selling it without warning was not a good idea, but they were entitled to sell it if they believed you abandoned it. Leaving goods in the hands of another is called a bailment, and it is subject to very specific rules under state law. Most states severely limit the time within which you may return to the holder and demand return of the goods, allow sale of abandoned goods, and limit the damages in the case of wrongfully lost or damaged goods. A Washington attorney might be able to give you more information about Washington's law in this regard.
If your receipt does not have a pickup date and they truly did not contact you to ask you to pick up the oven, then you might talk to the manager about selling you a different oven at a discount.
For example, if buying a new one would cost you $500 more than what you paid, you may be able to convince the manager to sell you the new one for less. Try to negotiate a deal, pointing out their failure to notify you and their failure to expressly identify when you had to pick it up (if, in fact, the receipt is silent as to when you were to take delivery).
Working out a deal is the best way to handle this. If the manager refuses to deal, take your money and purchase an oven elsewhere.
Using legal recourse--even a small claims lawsuit--is not at all practical because it would cost far too much to sue, much more than possible damages. And you seemingly did abandon the oven by leaving it with Sears for five months without contacting them. A judge would likely not be sympathetic.
I am licensed only in California and this response is provided as general information only. It is not intended to be legal advice. Legal advice must be based on the exact facts of the particular situation, and by necessity this forum is not appropriate for discussion of specific, exact facts. Contact a lawyer for more specific advice. My answer to your question on AVVO does not create an attorney-client relationship.
Have you searched thoroughly online etc to see if you can find that model oven refurbished elsewhere? if so, see what the price is. if it is about what you paid sears or less, take the money from Sears and buy the replacement. if the replacement is more then show that to sears and see if they will make up the difference. If they wont, and you purchase the replacement for more, then sue sears for the difference. Likely that would be in small claims court.