Not something openly purchasable on the web as far as I know(because I've also tried finding one in the past, and as expected I couldn't find any); you're better off actually hiring a decent programmer for this. And I'm guessing that you'd actually need a well optimized software to make it as quick as possible, because it's safe to assume that it's not only you that would have such a bot running.
Yeah, coming across these bots on market is difficult. Most of these will just be in-house made (for good reasons). Unfortunately, I don't know anybody who runs such a thing, probably a personal secret also. Though with some more research perhaps you can come closer to an answer, and maybe when you got something you can post on here 
Good luck.