Luka is a tough one... mostly because of how much she has going on accessory-wise. Two bits of advice ~
1) LAYERS will publish a Vocaloid mook in Japan this month. In it are full patterns and construction tutorials for basic Miku and Luka costumes. If you found a bookstore dealing in overseas books to order you a copy and are a US xs-m (the sizes covered), you would be golden in following that. Even in the case that you required a larger size, the patterns could be sized up through tracing and sizing with transparent pattern paper or carefully handled tissue paper. The construction process would remain the same.
I'm following their patterns to alter the front of my Len costume (adding a hand-sewn snap-on tie) and the instructions are clear as can be. Highly recommended
2) Luka's most difficult pieces involve elaborate accessories and quite a lot of craftiness. You'll have a hard time finding matches for the boots, so you'll probably want to make boot-covers. You'll need to make armwarmers (and the panels that attatch to them). You'll need to make the crazy brass-band-esque decoration at her chest and devise some way to attatch it. You'll need two waist belts. You'll need an armband. And you'll need a headset (easily altered from a tutorial for Miku and the twins). I would go so far as to BEGIN with your accessories. They'll be the most time-consuming as a set and, believe it or not, when finished, will cover the bulk of your completed costume. You don't want to be left figuring out your props and accessories last minute.
None of them (with the exception of the neck piece) are particularly hard to construct. You just need to hunt down materials, useable tutorials and advice for individual pieces as you go. If you make them all yourself, you can learn a lot about costuming just from this one project.