You now have a good idea of what a relative cost is when someone has a 'passing interest' and is 'fairly interested'. It's up to you how you think you should extrapolate that out for the big ticket items.
Okay, so of the items we know.
Cookbook
There's a vague, general interest in the item. Beside you, you notice Xanatos studying the item critically. You doubt he'd be particularly put out if you managed to snag it, but it looks like he's at least considering the item simply because it likely contains spells he's never seen before.
Xanatos consider is 5 on a 4 item.
Scrolls
Xanatos looks like he's mildly interested in the item, strangely enough. He probably wouldn't be too upset if you took a stab at it, but he's certainly displaying more interest than most of the other auctiongoers. The 'Drake Stone' fellow seems to take an interest too, but he's quickly shut down by what is clearly his superior. Pretty much every caster in the audience is dismissing this lot, especially the Brit in the bowler. He looks like he's had a few too many good meals to go in for this sort of thing, if you know what you're saying. Which you do. Because you're you.
Mildly intrestedis a 5 on a 4.
This seems to be the item Xanatos mentioned earlier. He gives you a sidelong glance as if to confirm your thoughts on the matter. It seems like he thinks your technological flair could jury rig some proper use out of an item that for anyone else is just a one way ticket out of this universe. Other than Xanatos, Monty Hall perks up a little at the mention of the key. He seems to be playing second fiddle to the blonde guy though, so possibly he won't be able to bid anything crazy high. You wonder why he would be interested in a magical key that opens doors to randomly selected dimensions.
Won't bid anything crazy high apparently translates to a 4. Since we won it outright.
Given this, we can probably extrapolate out that the 7 items, being about double, will have a doubled increase, as such a 9 is what we would be looking at for mild interest, and a 10 to guarantee against that.
Of the 4
Oh yes, this seems to be a very popular one. The dignified-looking British fellow in the bowler hat looks particularly interested at the mention of the 'Merlinian' encantus, and the weird magician guy with white hair next to him gets an elbow in the ribs. Janna looks like she's about to start salivating over the thought of the Morganian volume. Owen's posture shifts just a bit too, but you're not sure about which edition.
All sorts of people around the auction are interested in the talisman. Everyone from Xanatos to the bowler hat man look at the talisman with interest, even that one weird redhead in the back row. This is going to be one of the hottest items of the night.
Eh, you're not sure. The thing creeps you out, so you figure it'd probably creep everyone else out too. Janna might already be drooling over it, but she loves creepy stuff like that so she doesn't count.
Both the tailman and the Merlinian encantus are outright interest. Given we would need 10 points to secure them at mild, we would need more than 10, as such either of those should have us dump 17 points in. The other two are more of a gamble, the Morganian encantus has at best Owen interested, and even then only a bit of a posture shift, then again, Owen is defined by restraint, but we might see that as a mild interest. If so we could drop 10 on it, and gamble that there isn't really any interest in the Manual of Witchcraft and Alchemy so we can drop 7 there, but... eh? Or switch around, since Owen might be interested in the Merlinian one.
We could drop 9 points on one, but unlike round 2, there isn't a point refund if we don't win, so I'd rather not. Honestly, the Manual of Witchcraft and Alchemy would probably get us fighting the Sanderson sisters, which might be fun. Janna could use her first set of pathetic mages to crush beneath her heels.
EDIT: Also, we could forge the devil's signature, identity theft the devil!
