I have seen Tigers as low as $350 before, however that was a very young, new import. I would not buy one that small or young, they really are not very hardy at that size. I know I struggled to keep mine alive when I had him. After about 6 month or so it did get better however. Just something to consider.
Most go for about $550+ from what I have seen. Many are over $1000 for one with some size on it. With a Tiger you really want to get a bigger one. They are not like motoros. I am sure you have done your homework, but think hard before deciding to get one of these guys.