Maybe keep an eye out on The New Beverly's facebook page (Tarantino's theater)? They just posted this fun TV guide cover from the movie:
I also grabbed one of these programs from opening weekend at the Chinese Theater that had advertisements from products in the movie. I can't remember if it had one for the dog food (I sold it on eBay a week later).
Then there's this poster for one of the spaghetti westerns (I can't remember where I got this image):
That is a sweet cover! Mad magazine released the same cover (of mad) that Rick Dalton has framed in his house. There's a few differences ie the date and price but definitely a good jumping off point for a screen accurate cover.