It’s very widespread, though in my experience it’s usually $5k-20k type concessions. Personally, I have not come across any that were over 3% of the sales price, but they are out there. It will get worse as credit tightens.
It is inflating the market and it is one reason why most indicators of value in SD are not showing their true levels of decline. As an appraiser, I contact every agent for the comps I use and back out any concessions they disclose from the sales price of that particular comp. If you know what you’re looking for these are fairly easy to spot in the MLS.
I’ve emailed Sandicor several times requesting that they update their rules to REQUIRE agents to disclose any sales concessions in the MLS once the deal closes. They refuse. This is another example of why prices appear to be sticky on the way down.