I'm not sure how it would work exactly, but Shapechange uses a focus of 1,500gp. The Spell-Like ability states: "and a spell with a costly material component instead costs her 10 times that amount in XP." Since it's a focus, you'd keep the focus? Pay 15,000XP once and never have to use the focus? Pay 15,000XP each time you cast the spell?
Time Stop doesn't have a costly material component, and is always handy to have around.
Meteor Swarm doesn't have a material component either.
Are those the only spells you're planning on making Spell-Like abilities? Losing a 9th-level slot is no small thing...
Slim