You can order the Dragonfly .15 ARF and a Thunder Tiger GP-15 engine both for $114.95 ($67.95 + $47.00) at http://www.thundertiger4u.com The Dragonfly is rated for a .10 to a .15 2-stroke, so the GP-10 would work as well. There is only a $1 difference between the price of the two engines, though.

If you're enjoying the Dragonfly and you just can't keep that darned Magnum .15 bolted together, maybe it's worth springing for a new engine. You mentioned that you have a .10-sized engine already, that could also be worth a try.