Spell trap costs?

[Lavan]

Came across the rules for spell traps in the DMG and I really would like to use them but the rules seem a little weird. It says spell traps only have a cost if you hire an npc to cast the spell. Does that mean all you pay is the xp cost if you create it yourself or is there not even an xp cost? I'm also not entirely sure what the difference between a magic trap and a spell trap is.

[Kelb_Panthera]

Ahem, note the table here (http://www.d20srd.org/srd/traps.htm#magicDeviceTrapCost).

It's in the DMG too but I don't have mine handy for a page reference.

[Lavan]

"Spell Trap Cost
A spell trap has a cost only if the builder must hire an NPC spellcaster to cast it."

Its right below the table. As far as I can tell spell traps and magic traps do the same thing, so why the cost difference?

[Kelb_Panthera]

"Spell Trap Cost
A spell trap has a cost only if the builder must hire an NPC spellcaster to cast it."

Its right below the table. As far as I can tell spell traps and magic traps do the same thing, so why the cost difference?

Because "spell trap" refers to spell effects that yield what are effectively magical traps. E.g. symbol of death or glyph of warding.