Pretty clever. Illegal in the UK, mind, but still pretty clever.

Maybe an automated generated sign?

It looks like it may have been a typo, when I worked at Sears a while ago we'd often get weird signs adding to a price instead of subtracting. When making a sign (especially a custom one) you would select the item on a computer and then put the reduction in. The computer automatically reduces the price of the item by the amount you type in. Sometimes, especially with newer people, they would put a '-' before the reduction thinking this was necessary to create a reduction when it actually has the opposite effect, and the sign that printed out would look exactly like this one. (except it wouldn't show the original price when it is raised).

I'm also thinking it's automatically generated. I think it's a mistake and not meant to be intentionally misleading. Apparently they need to code 'if newprice > oldprice then printsign=false'. Even Walmart (or not so 'even') is notorious for not paying attention to higher prices on their 'Rollback' signs.

It was originally posted up on the Consumerist.
http://consumerist.com/consumer/badvertising/toys-r-us-invites-you-to-save-+10-319089.php

Saw your post linked to from Boing Boing today.

You should pass this on to thedailywtf.com, it's a blog about hideous programming errors and they have a special section called Error'd devoted to signs and posters that got messed up by software bugs.

My favourite was the chocolate raisins which listed their ingredients as SELECT * FROM etc.

well, i doubt its a mistake because at the bottom it explains that the original price was $10 less.

It probably is a mistake.
The original price WAS $249.99 as the sign clearly shows.

Whoever entered the item for a discount probably typed -10 instead of 10 and the computer printed teh only logical thing:
249.99 - (-10) = $259.99

Step One: Be smarter than the computer

This looks more like inadequate error checking coupled with a poorly-trained employee rather than a deliberate attempt to raise the price. Add to it a moron who didn't notice that the sign came out stupid.

A few months ago I found a clearance sign that reduced the product $0.

A client of mine once sent the U.S. Immigration and Naturalization Service (which is now U.S. Citizenship and Immigration Services) an application that had no filing fee, so, naturally, he didn't enclose any payment. The INS mailed back the application with a letter saying it was being rejected because the applicant had not enclosed the correct fee of "$0.00."