Unfortunately the current technique I use is by hand. If someone knew some way to rip books from PDF to some text parsable format, it wouldn't be too difficult to get at least most of the information in there. There would likely still be some stuff that would have to be done by hand though. So I guess it is kinda pointless. I do most of it copy-paste style, I usually just have to change 2 fields.
Having the books in PDF format (which have been OCR'ed) is a pretty easy thing to obtain, and i'm sure that they will be torrentable soon after release for all source material we do not have our hands on. (Bleeding Heart Plug: Please buy the books if you plan on downloading the PDF).
After that, I looked at the magic item table list (top of page PHB 228) and I think that contains all the information that you would need to parse with the exception of the exact page of the source material. You could cut/paste the whole table into a text file and have a program parse all the data you needed right?
1 Magic +1 360 Any
2 Dwarven +1 520 Chain, Scale, Plate
2 Razor +1 520 Scale
3 Curseforged +1 680 Chain, Scale
3 Delver’s +1 680 Any
3 Eladrin +1 680 Chain
3 Fireburst +1 680 Cloth
3 Sylvan +1 680 Cloth, Leather, Hide
Read one line at a time
Rip Lvl, name, Enhancement, Price, Categorytype
I'm still not exactly sure how you're category types work from reading the XML files, but I'm pretty sure you probably do

.
As far as selectability goes, I personally don't care which items get listed if i can filter out the weapon/armor types. Having noone in my current party wearing Hide for instance, would be nice to not have Magic Hide generated in parcels. Same would go for weapon types.
Breaking Thought: If you reeeeaaaaalllly wanted to get fancy, you could do a crazy variable select. No Hide <+3, No scale <+2, No Mace <+3, or you could do it by level base:
You have one cleric in the party who favors the mace, and is the only one who can use a mace. His mace is currently a level 4 magic item. It will be very unlikely that he will want a new mace that is level 4 or lower.
Obviously this is much more complex, but hey.. i'm a dreamer.
