To a collector, that castle deed is going to be worth A LOT. Consider this. A castle, when bought back in the day like this, was worth 5 million. I would assume it is worth atleast 5 times that now, to the right person. Those house deeds are so rare now, especially a castle one (due to the fact that back then when purchasing castle deeds cost 5 mill, people usually used them. Not many people had 5 mill to throw around like this back then.), that there is no standard price. This is just a guess, but you may have an item there that only a few people in all of the shards put together have. You could fetch a very nice price.

The spellbook is one of those things that I personally have never seen before, so I can not give you a solid price on that. I would assume it's a bugged item, and therefore extremely rare. If you need the gold, sell it, but I would keep it. You may be one of the only people to have one.

edit: forgot. I would ballpark that castle deed atleast 25, to as much as 50, maybe more, depending on how rich of a collector you can find on baja. The spellbook is a glitched item, which in turn could fetch an insanely high price. I would refrain from selling that item out in the public, because it is a glitched item, and if reported to a GM, they do have the right to delete it without any compensation to you. I've had this done to me a long time ago, with the only explanation being that I had an item that didn't belong in the game, therefore it was deleted.

sorry one more edit. Just for note. These items are ONLY valueable to the right person. To the regular joe, such as myself, they aren't worth anything. You have to just find the right buyer, and take what you believe to be just compensation for the item, since there is no standard price on rares such as these.