I use in all of my pylons AR 6255,cheap and reliable.
My latest fuses are full carbon,so i have to take the antennas out.
Try to avoid all BEC or S-Bec stuff, for me a simlpe 4cell 250Nimh for RX is the best solution.
Try to save weight,you will earn agility and reliability in daily use.
There are some cheap options for the drivetrain around,its better to save money with motors than with airframes or servos.
Almost every inrunner in the right size (120-180g) and with the right Kv(3000-3500 for 4S or 2300-2600 for 5S) is able to get an F5d on a proper speed level.
The difference between budget- and high-end motors is mainly the efficiency(and for sure the quality
You wount feel the eta difference (for example 5%)that much in power but the high quality motor has much less waste-heat so you are able to run much longer with same power or run the same time with much higher power.
For competition Eta is very important because energy is limited,for fun racing even cheap motors will do but be carefull with running time.
Anyway, a pylonrace is done in 55-70sek at about 1Kw input-power(static about1,6Kw) do not try 3 minutes even when the battery would give that option.
Experience showed that its better to go 70sek flat-out than doing 10 times 10 sek bursts!
Avoid longer part throttle passages,for the first flights better use a smaller prop.
Some testet budget Motor options :
Feigao 380-12L for 5s at 4,7x4,7
ARC 28-58-1 at 5,2x5,2 at 4S
Keda SKF-2865/5D at 5s 4,7x4,7
Even chinese budget controllers(like turnigy or Sunrise/Himodel) work on these 2-4pole Motors,at 4S i would recommend 120A,at 5S 80-100A.
The megas are good compromise,very good performance and reliability on a mid-price level.
Again,better motors/controllers give better performance but i would rather save money here instead of taking cheap airframes or Rx stuff!!!!
The currentdraw of pylonracer in flight is about 75A at 4s or 55A at 5S, so most of the lipos will do the job.
Use small ones to save weight,2200-2600 for 4s or 1800-2000 for 5S.
Turnigy 40C series is fine, 65C series is better but reliability is still to proove.
Finaly, the most important thing.
Flutter is the evil enemy of pylonracers.
Linkage is the key,better to spend time here than thinking about better drives!
Use the complete throw of servo and reduce flap/elevator trow if nessecary by linkage.
Deal throw to lingage stiffness and force,if the plane is light, you do not even need flaperons to slow it down for landing!
Do not spend too much time for perfect surfaces or servo-covers.For the first flights it will be fast enough.
Having improvement-options keep you in the game!
So good luck and have fun!!