[gurps] Energy Cost of Magic Items

[midnightwind at comcast.net]

OK!  Now I'm confusing myself--

A little while ago, there was a brief discussion about the spell 'Inscribe' and its utility in making an enchanted pen (energy to create: 30).  It was effectively argued that to subsequently use such a device to create a piece of art (something that would take longer than the spell duration of 1 minute) would not cost the user any fatigue.  The wording was subtle, but I tended to agree.

I'm going through Magic 4e again with this in mind, and things like the spell 'Heat' and 'Clean' are confusing me.  'Clean' (energy cost to create: 100) costs 2 Fat to cast as a spell. The wording 'The item must touch the affected area' is not dissimilar to the 'Inscribe' item description '... can leave inscriptions without ever needing ink or paint.'

Or 'Heat'-- energy cost to create is 400, but there is no decription of the item.  The spell costs 1 Fat per minute (to raise the temperature of a fist-sized object 20 degrees)...  Does the item cost fat to heat it?  One could place a Limit spell on it to hold it at 400 degrees and make a nice hotplate...  If one had to touch it to turn if off, that would be a pain... handles are good things.

Anyway, how would folks resolve these types of issues?  (I'm thinkning here about economics in a magical society, where magic is being employed for conveniences... wouldn't that drive a 'realistic' fantasy society?  If I'm a rich noble, do I buy the magic sword, or do I buy the forced air cooling unit, the cookstove, and the laundry cleaning unit for my wife, first?  Seriously.  

-vk