I’m throwing this into a thread on discourse as there may be need for a discussion around better part sourcing. Here are the sources and costs for v3 parts I have ordered so far (it is assumed that the printed parts are handled elsewhere)
20/20 t-slot, 3 of these (1220mm) will cover the needs for the rotator, from Amazon, $43 with shipping: http://www.amazon.com/gp/product/B001F0K4NW?psc=1&redirect=true&ref_=od_aui_detailpages00
I went to boltdepot.com for the metrics nuts and bolts (socket m5, socket m3, set screws, etc). I spent $39 here including shipping but that also included a bit of extra hardware for spares and electronics mounting.
NEMA17 motor mount, $10 with shipping: http://www.ebay.com/itm/201384754911
Small timing pulley x2 ($6 total): http://www.ebay.com/itm/111662829435
Large timing pulley x2 ($6 total): http://www.ebay.com/itm/121650622279
PVC ball bearings x4 ($20 total): http://www.ebay.com/itm/121460828942
Worm gear ball bearings $3: http://www.ebay.com/itm/231603619368
Small timing belt, $3.50: http://www.ebay.com/itm/141216592510
Large timing belt, $3.80: http://www.ebay.com/itm/141216598190
2020 hidden inside corner bracket x36, $33 with shipping: http://www.aliexpress.com/item/T-Slot-Connector-90-degree-Angle-Bracket-Inner-Inside-Corner-Brackets-for-20-Series-with-Screw/1929382240.html
I have not bought any slot-6 nuts, rather half height M5 nuts and washers in conjunction with https://www.thingiverse.com/thing:28788
Hope this helps,
-Corey