BHH has the Zen 300 for 199
http://www.bhhanson.com/engines.htm
Bonzi makes a good clutch
Avoid duel rudder systems as they are more weight, complicated - hard to keep aligned and no real improvement on steering (I have both here - my son runs WHH duel and it's a PITA)
Think simple and less complicated - complicated = more to go wrong. Stick to 'name brand' hardware like SpeedMaster, Insane, etc,
Just my 2 cents
Randy