Brushed motors esp the ones that came with the highwind are inefficient which translates to heat.
I just run mine at 2s(8.4v) and i swapped out the 380s with 480s.
you could probably run it for a while more until the electronic burn out.
Then swap it with 2 30 amp esc or 1 50amp esc and you should be having some fun scale speed running NQD.
i use mine as a recovery boat now you can see my old NQD at the end of the footage.

http://www.rcgroups.com/forums/showt...54#post5903637

edit: oops! i did not see the $30 limit. now you gonna need to be creative.