Soo..I'm definitely in the lower class when it comes to sp. Is it worth it to spend 3mil on level 57 of item hunt? I know he will only give me like 165'000....What do you guys think?

The second Chase starts asking for items that cost more than the reward, I deliberately fail and restart the quests. I think I spent 1 mil on an item once, thinking it would be worth it; never again.

IMO, The higher quests aren't worth it unless you're specifically going for that achievement. And if you are, be prepared to spend a lot more. It gets more expensive the higher level you go.

Awesome thanks! Chase can buy his own ridiculously expensive beanbag

If you wait until level 75+ to quit, you'll unlock him as a battle challenger (but he's, I think, an Impossible challenger, so you're probably not in a rush to unlock him). Sometimes you might get lucky enough to get to that level while just playing for rewards, so it's worth the wait if you're not interested/can't battle him yet.

Another thing to keep in mind is that you can only finish Item Hunt once (and like said, it's going to be really expensive to do so) so if you play for sP, it's much better to cancel when the cost of the item outweighs the reward you'll get. Sometimes I'll gamble and spend a little bit more (but definitely not 3m) in the hopes that my next item will be cheaper and the reward will make up for it, but I only play it for sP and I'm not interested in finishing :P