Idea from a monk player

[ARandomGod]

This is all well and good, but where did he get the masterwork hands from?

Good breeding. Either that or something really, really painful.

Have you any idea how amazing the existence of hands are? I mean, YOU try designing something that spectacular. Brilliant guys at MIT have been trying for years and their best still doesn't match the craftsmanship your hands have. I mean... the precision, the speed, the fluidity, the versitility, the sensitivity... it's unbelievable, really. I'd say your hands are more than masterwork, they're like epic craftsmanship or something.

Now you're going realistic! Completely true, of course.

Back to topic and my input...
Gauntlets or bracers would be good magic item slots for enchantment of fists. Tatoo's that take up these slots would be quite appropriate. Tatoo's that don't should be considered slotless and cost x2.

Amulet of Mighty Fists was priced (so it's said) at 150%, for being in a non-affinity slot. Use that to figure the base price for the enhancement, the item(s) your considering, or the tatoo, and it should be balanced.

Edit: Items that take up ONE of these slots would be appropriate. Items that take up both would be interesting... possibly costing 50% of an item that only takes up one? But now you're wading deep into houserules.