It looks like a 315 Mhz repeater will do the job: FCC ID HYQ14ACX Denso Corporation Electronic Key Bob Wilson
Bob, I've also been trying to find one of these booster/repeaters, but no luck so far. The item you found is the part number for our key fobs. I found that part on Ebay and it has a picture of our fob. I looked on the back of my fob and the part number is listed there. If we keep looking I think we will find the hacker part. Happy hunting. Cheers. Toyota Smart Key Fob Remote Keyless FCC ID HYQ14ACX 3 Buttons | eBay
Forbes: Vulnerability In Car Keyless Entry Systems Allows Anyone To Open And Steal Your Vehicle NY Times: Keeping Your Car Safe From Electronic Thieves SFIST: Thief Hacks Car's Keyless Entry To Steal $15,000 Bike In Sausalito FinanceTwitter: Here's how a $17 gadget breaks into your car's keyless entry system AFR: Why keeping your car keys in the freezer may protect you from digital thieves Ars Technica: New York Times columnist falls prey to signal repeater car burglary Jalopnik: Tech Blogger Says He Watched As Youths Wirelessly Broke Into His Car NICB: Thieves Caught on Camera Using Mystery Device to Unlock Vehicles Business Insider: Power Amplifiers Helping Car Thieves
Still waiting to see the links for these devices at eBay and Amazon that many of these stories mention... Any serious technical journalist would have got hold of one long ago and done some tests.