there is also the hpi rotostart unit.
http://www2.towerhobbies.com/cgi-bin...&I=LXFET0&P=ML
or for the upgraded version:
http://www2.towerhobbies.com/cgi-bin...?&I=LXMVE0&P=7
The only problem with those is that you need to buy a 7.2v battery and charger which could end up getting expensive.