What you're wanting to get into requires a reputation. I wouldn't be to inclined to buy a tape from some shmoe that I've never heard of. I would be inclined to buy something like a DVD (who uses tape anymore) from some one like Bob Applegate (on king snakes), Bill and Kathy Love (on corn snakes) and Dr. Bryon Fry (on venomous) just to name a few. These people are experts in their respective fields and have reputation that's world renown.
Now I'm not trying to be mean or anything but I wouldn't buy them from some kid who hasn't really done anything in the world of herps and is basically regurgitating the information they've learned from care sheets.