the latest kit is a bolt on replacement,,, has spare parts so if you did crash you just get a motor mount, inner frame mount, tube, etc.
I believe the kits today are $119 for all four, the next kits in a month are under a hundred, have hardware to also coax, or to bail the landing gear all together. replacement part cost is super low,,, this kit in particular breaks away saving the frame similar to how the dji ones do, they just have zero rotational twist, no horizonatal or vertical flex..... can run stock motors on up to 45-50 minute flight worth of motor and flight pack for a minimal investment as these things go.
the arms are our kit so take my word for what it's worth, the v.2 kits will be at tbs first, then our webshop a couple weeks later.
http://team-blacksheep.com/products/prod:aerial_mob_extension
those are still the v1.5 and there a good kit, it just doesn't have the registration in the tubes to make them bolt and play without messing with motor angles.....
I'm personally flying a set of the pre production v.2 and am stoked there finaly a perfect kit....