If you own a (1) jewel with 40ed/15ias it is worth a lot and you should consider putting such a wealth into your character. Nat's armors are virtually unsellable, so think about it. If you have 2 jewels, then no problem, they can be found again quite easily.
I would read some stickied guides in the Assa forum, or check the ones in the Strategy Compendium
I don't believe Nat's armor is advised for many builds though, cheap options that could work are (again, depending on build) treachery or vipermagi, but most builds will advise you to use enigma/bramble/other expensive options.
Sorry I can't be more helpful, also, if you decide to open a thread in the assa forum, make sure to specify what build you are trying and other pieces of equipment you use/want to use.