We usually don't really add value for spells; it's usually tricky as it depends greatly on the personal appraisal; we're after common trading points in pure. The only situations where they are taken into account is where it is evident that the spells add significant value, reflected in a common trading point: spelled max heads as an example typically sell slightly higher than regular ones (based on their sales), but most regular cosmetics generally remain unaffected, with an occasional exception for footprint spells. For backpack.tf pricing, they are generally appraised based on their generic counterpart