How difficult an item is to steal is based only on appraisal price and weight.
Update: Any item teaches until at least 30 ranks:  (Testing indicates the easiest items teach to 38 ranks.)
If you add other provinces, use the monetary conversion factors to put the app price in lirums or dokoras into kronar. (lirums * 1.25 = kronars, dokoras * 1.385 = kronars) If you don't convert, please notate that by adding the currency so someone else can convert it.
Triviality rank is the minimum rank at which an item will no longer teach. This is based solely off of unbonused base stealing (exp thievery). I have added a few triviality ranks but these might not be the minimums. If you are able to verify a minimum triviality ranks (can steal and learn at X, at X+1 I get the trivial message) please add it.
Stealing List By Province
Crossing Stealing List
The following list was made after the update to stealing that Javac did in 2016, and is mostly accurate after 50 ranks. Prior to 50 ranks, the thief doing the marking did not have enough appraisal skill to be accurate in most assessments.
Subjective tip: The best learning-to-risk ratio is with an item that is +2 in both columns. Steal 4 items per shop, 2 for Orielda's Blossoms (the third attempt will always catch you.) At 425 ranks, I only need to hit 8 shops per run to mindlock.