Hi All
An Easy Start solution for 500 is to use an existing HF rig modified for 5
mhz tx at low power, then shape the sine wave to sq wave  with a single chip
and divide by 10 with another chip then a driver chip to a fet pa, then lpf
and you are in business. A single fet class E pa is sure fire and so simple
to build. Mine went first time.
My solution for an exciter is an IC 706 on 5 mhz and also used on 13.7 mhz
for LF used. This is a vy stable sig source.
If anyone needs more info about type of chips etc let me know.
73 de Mal/G3KEV