buy a nitro savage roller, or a used complete one off ebay sometimes there cheaper. I got one - radio for $130 shipped a few months back that I rebuilt into a flux. You can resell the nitro parts later. Or get a savage X RTR for $400 and resell the F4.6 for $125-$150 on ebay, and get the rebate before october 30th to make it around $200 (not counting towers coupon codes)
But the $7 flux idle gear
buy the flux battery compartments $30ish
buy the flux motor mount set $30ish
buy the 5T kit $150
but a ESC/motor I use a $200 HW 150A 2000kv combo and like it in my converted savage.
Buy flux dogbones(or the HD) the stock nitro savages will twist.(If getting the X this step might not be needed)

But in all honestly I did my nitro conversion like 4 weeks b4 HPI released the $500 flux or I would have probably just bought that to have the BP gears in it seeing I spent a similar amount on making mine.